Periodontal Ligament Flashcards
How is PDL formed
HERS separates dental papilla and follicle. Dental follicle cells differentiate to form fibroblasts which product collagen fibres responsible for forming PDL
Properties of PDL
Hourglass shaped. Reduced in non-functional or unerupted teeth (usually 0.2-0.4mm). Soft, richly vascular. High cellularity turnover rate
Function of PDL
Attach cementum to lamina dura (alveolar bone that surrounds tooth).
Support tooth in socket, prevent loosening of teeth.
Sensory function since rich with nerve endings that are receptors for pain and pressure.
Well vascularised hence able to maintain vitality of various cells.
Contain undifferentiated ectomesenchymal cells for
maintenance, repair and regeneration.
What are the 5 types of principal fibres
Alveolar crest: resist vertical and intrusive forces, run apically to attach just below CEJ
Oblique fibres: resist vertical and intrusive forces, run coronally from cementum to alveolar bone (main support against masticatory forces)
Apical fibres: at base of socket attaching to root apex, resist vertical forces
Inter radicular fibres: from cementum to crest of interradicular bone, resist vertical and lateral forces
Horizontal crest: resist horizontal and tipping forces, perpendicular to long axis of tooth
What are the components of the periodontal ligament
Collagen formed by fibroblasts which originate from dental follicle cells
Reticular fibres (type 3 collagen) which form a supporting mesh
Elastic fibres at walls of blood vessels
Oxytalan fibres which are immature elastic fibres present in PDL, attached to cementum
Glycosaminoglycans and proteoglycans
Blood supply of periodontal ligament
Derived from superior and inferior alveolar arteries, lingual and palatine arteries from gingiva. Vessels branch and anastomose to form capillary plexus which encircle tooth within connective tissue. Many fenestrated capillaries present
What happens to PDL with age
Fewer fibroblasts. More irregular structure. More oxytalan (immature elastic fibres). Hypofunction due to decreased width. Decreased PDL cell proliferation impairing repair potential. Decreased organic matrix production
