الرباط حول السني Periodontal Ligament

Sub topics
Topic 1. Development of Periodontal Ligament
Topic 2. Histology of Periodontal Ligament

1 Development of Periodontal Ligament

Periodontal ligament is connective tissue that connects the cementum of the root to the alveolar bone hence the name ligament
During the initial stages of root formation the follicular cells show increased proliferation
The innermost cells of the follicle near the forming root differentiate into cementoblasts and the outer most cells differentiate into osteoblasts
The centrally located cells differentiate into fibroblasts


Fibroblasts produce the periodontal ligament fibres
They get embedded in the developing cementum and alveolar bone
At first, all the developing fibres of the periodontal ligament run obliquely in a coronal direction from tooth to bone. This changes as the tooth erupts
The periodontal ligament is always in a state of remodelling which is because the fibroblast synthesize and secrete collagen
The functions of periodontal ligament are formative, supportive, protective, sensory and nutritive

2 Histology of Periodontal Ligament
Periodontal ligament is composed of collagen fibres, nerves , blood vessels and ligament cells
The main fibres are the principal fibres and additional fibres are oxytalan fibres

Principal fibres
The fibre bundles that exit the cementum and alveolar bone and form the periodontal ligament are called principal fibres. According to the location of these fibres they can be dentoalveolar fibres or gingival fibres

Dentoalveolar fibre group
Apical fibre group – near the apical area of the root
Oblique fibre group – immediately above apical group
Horizontal fibre group – near the midroot
Alveolar crest group – near the cervical region
Interradicular group – between two roots


Gingival fibre group
Transseptal fibres– cervical tooth to tooth
Attached gingival – cervical tooth to attached gingiva
Free gingival fibres– cervical tooth to free gingiva
Circumferential fibres– continuous around the neck of the tooth

Oxytalan fibres
Apart from principal fibres additional fine fibres appear in the periodontal ligament that are called oxytalan fibres
These fibres support the principal fibres system and are considered to be part of the indifferent fibre plexus
They are elastic-like and appear around the vessel walls




Vascular and Nerve supply
There spaces between the fibre bundles called the interstitial spaces


The interstitial spaces contain blood vessels, lymph channels, and nerves
These structures help maintain the vitality of the periodontal ligament

Ligament cells
The most common cells of the ligament are fibroblasts
Other cells that are found are cementoblasts, osteoblasts and epithelial rests