Periodontal ligament
Desmodontium (ligamentum periodontale)
Also known as: PDL, periodontal membrane
The periodontal ligament is a thin layer of dense fibrous connective tissue that suspends each tooth in its bony socket. It forms the gomphosis joint and acts as a shock absorber and pressure sensor.
Overview
The ligament is only a fraction of a millimetre wide, about 0.2 mm. It consists mainly of type I collagen bundles running from the cementum to the alveolar bone, both ends embedded as Sharpey fibres. The principal fibre groups are named by position and direction: alveolar crest, horizontal, oblique (the largest group, which turns biting forces into tension on the bone), apical and interradicular.
Between the fibres are fibroblasts, cementoblasts, osteoblasts and osteoclasts, epithelial rests of Malassez, blood vessels and mechanoreceptors. The mechanoreceptors give exquisite information about bite force and tooth position and feed into jaw reflexes.
- Location
The space between the root cementum and the alveolar bone (lamina dura) of the socket.
Anatomy
- Innervation
Branches of the superior and inferior alveolar nerves (V2 and V3).
- Arterial supply
Alveolar arteries via vessels from the alveolar bone, the gingiva and the apical region.
Function
- Suspends the tooth and absorbs masticatory loads (gomphosis).
- Proprioception and touch–pressure sensation from the tooth.
- Nourishes the cementum.
- Remodelling: pressure leads to bone resorption and tension to bone deposition, which allows physiological drift and orthodontic tooth movement.
Clinical significance
Periodontitis and tooth mobility
Chronic bacterial inflammation, for example with Porphyromonas gingivalis, destroys ligament fibres and alveolar bone. Deep periodontal pockets, mobility and eventually tooth loss follow. On radiographs a widened ligament space is an early sign of trauma or infection.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.