CLINICAL CORRELATION: Bone, PDL, and the cementum together form a functional unit of special importance when the orthodontic tooth movement is undertaken. Orthodontic forces causes compression and constriction of blood vessels, soft tissue changes occur.
Hence loss of alveolar bone occurs, now blood flow occurs in the spaces. And the mesenchymal cells of PDL repair the tissues.
MAINTAINENCE: Tissues are maintained under the influence of heavy masticatory forces.
SHOCK ABSORBER : It absorbs the shock of chewing.
PDL FORMATION PDL is formed within the developing dental follicle . Ligament space consists of unorganized connective tissue with short fiber bundles extending into it from bone and cemental surfaces. Ligament mesenchymal cells begin to secrete collagen (mainly collagen type I). The developing periodontal ligament fiber bundles extend into the unorganized ligament space from both the cementum surface and the surface of the alveolar bone.
The horizontal fibers termed as alveolar crest fibers have become oblique once again but with the difference that now the CEJ has reversed its relation to the alveolar attachment and is positioned in a coronal direction.
Only after the teeth come into function do the fiber bundles of the PDL thicken appreciably.