Periodontitis (also called gum disease, periodontal disease) is an infectious disease affecting the gums, the tooth attachment to the jaw bone, and the bone itself. It is estimated to affect more than half of adults.
Irregular hygiene leads to plaque building up around your teeth and an inflammation of the gums. They become red, sometimes swollen and bleed when pressure is applied. This is the early stage of gum disease called gingivitis. At this stage the condition is reversible without permanent damage. Professional removal of the deposits on the teeth surfaces and establishing good oral hygiene habits will to quickly improve the gum health.
If untreated, the inflammation soon starts affecting the tissue which attaches the gum to the teeth and the jaw bone. The gum starts receding and withdrawing from the tooth surface creating the so-called pockets, which serve as a trap for debris and are impossible to clean by the normal oral hygiene routine. The plaque deposits harden, creating calculus under the gums. That serves as an additional irritation and retention factor. The infection starts penetrating into the bone itself, leading to a reaction from the body causing the diseased bone to disappear. Over time this process can advance to a stage where there is not enough support for the teeth anymore and they become loose or even fall out on their own.