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Informed Health Online [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-.

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Informed Health Online [Internet].

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How does the periodontium work?

Created: ; Last Update: October 4, 2011.

The periodontium is responsible for keeping our teeth firmly anchored. It has four parts:

  • tooth sockets (dental alveoli)
  • periodontal ligament (periodontium)
  • cementum
  • gums (gingiva)

The holes in the jaws that contain the roots of the teeth are called tooth sockets, or dental alveoli. The jaws and the walls of the tooth sockets are made up of bone tissue. This part of the periodontium is not usually visible.


The teeth are connected with the walls of the tooth sockets and anchored in the jaws by the periodontal ligament and the cementum. The ligament is made up of connective tissue and contains collagen fibers. These fibers are especially strong so that the teeth can withstand the great pressure put on them while we chew. The teeth can also move slightly in the ligament to compensate for the pressure exerted by chewing. In contrast, dental implants are firmly attached to the jaw bone and are not able to move. In addition to connective tissue and collagen fibers, the ligament contains blood vessels and nerves: the blood vessels supply the ligament with nutrients, while the nerves are responsible for the sensation of pressure and help to control the amount of force used while chewing.  

The actual tooth has an outer layer of cementum around its root. The cementum is mostly made up of minerals, but also contains collagen fibers. It is very tightly connected to the ligament, connecting the root of the tooth to the rest of the periodontium. The cementum gradually changes to dental enamel near the neck of the tooth.

The gums (gingiva) cover and protect the ligament and the neck of the tooth. It is usually the only visible part of the periodontium. The gums fit tightly around the teeth like a collar. Where they meet the teeth, they turn inward somewhat, forming a narrow groove.

The gum tissue can easily become inflamed. Inflammation of the gums (gingivitis) can be visible as bleeding gums, but often does not cause any symptoms. Sometimes inflammation of the gum tissue can lead to periodontitis. Periodontitis is an inflammation of the periodontium that attacks the gums as well as the bone of the jaw and can cause more serious problems up to and including loss of teeth.

Author: Institute for Quality and Efficiency in Health Care (IQWiG)

© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK65282
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