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The periodontal ligament is the soft connective tissue between the cementum and alveolar bone. It has an hourglass shape that is thinnest in the middle and widens coronally and apically. It develops from the dental follicle during tooth eruption as collagen fibers form and attach to the cementum and bone. The principal fibers include the transseptal, alveolar crest, horizontal, oblique, apical, and interradicular groups. The periodontal ligament contains collagen fibers, cellular elements like fibroblasts, and ground substances such as glycosaminoglycans and glycoproteins. It receives its blood supply from the alveolar arteries and has a fenestrated capillary network.

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Periodontal Ligament PRESENTED BY DR ASIF K DEPARTMENT OF PERIODONTICS
• Periodontal ligament is the soft, specialized connective tissue situated between the cementum covering the root of the tooth and bone forming the socket wall
• Its width ranges from 0.15 to 0.38mm. • Periodontal ligament’s shape is like an hourglass apicocoronally. • Periodontal ligament is thinnest at the axis of rotation inthe middle and widens coronally and apically
• As the crown approaches the oral mucosa during tooth eruption, the fibroblasts of dental follicle become active and start producing collagen fibrils. • These fibers initially lack orientation, but they soon acquire an orientation oblique to the tooth. • The first collagen bundles appear in the region immediately apical to the cementoenamel junction and give rise to the gingivodental fiber groups. • As tooth eruption progresses, additional oblique fibers appear and become attached to the newly formed cementum and bone. • The transseptal and alveolar crest fibers develop when the tooth merges into the oral cavity. • Alveolar bone deposition occurs simultaneously with periodontal ligament organization. Development
• During eruption, cemental Sharpey’s fibers appear first, followed by Sharpey’s fibers emerging frombone. • Sharpey’s fibers of bone are fewer in number and more widely spaced than those emerging from the cementum. • At a later stage, alveolar fibers extend into the middle zone to join the lengthening cemental fibers and attain their classic orientation, thickness and strength when occlusal function is established.
CONSTITUENTS • A. Periodontal ligament fibers • B. Cellular elements • C. Ground substances i. Glycosaminoglycans ii. Glycoproteins
Periodontal Ligament Fibers • Mainly collagen and oxytalan fibres • Elastic fibers are present only in the wall of bloodvessels • Oxytalan are immature elastic fiber they support the blood vessels of periodontal ligament.
Collagen • Types I, III,V, VI, XII of collagen are present in periodontal ligament • Collagen is synthesized by fibroblasts, chondroblasts,osteoblasts, odontoblasts and other cells • It is secreted in an inactive form called as procollagen  converted into tropocollagen polymerized into collagen fibrils aggregated into collagen bundles by the formation of crosslinkages. • There is rapid turnover rate of periodontal ligament collagen,with half life of only 10 – 15 days, which is about 5 times faster than gingival collagen.
Principal fibers of periodontal ligament •1. Transseptal group Functions: • Reconstructed even after destruction of the alveolar bone has occurred in the periodontal disease. • Responsible for returning teeth to their original state after orthodontictherapy. Position: • Extends interproximally over alveolar bone crest and embedded in the cementum of adjacent teeth
Principal fibers of periodontal ligament 2. Alveolar crest group • Functions: (i) Prevent extrusion (ii) Prevent lateral tooth movements • Position: Extends obliquely from the cementumjust beneath the junctional epithelium to the alveolar crest.
Principal fibers of periodontal ligament 3. Horizontal group Position: Extends at right angles to the long axis of the tooth from cementum to alveolar bone.
Principal fibers of periodontal ligament 4.Oblique group Functions: (i) Bear vertical masticatory stresses (ii) Transform vertical stress into tension on the alveolar bone. Position: Extends from the cementum in a coronal direction obliquely to the bone.
Principal fibers of periodontal ligament 5.Apical group Functions: (i) Prevents tooth tipping (ii) Resists luxation (iii)Protects neurovascular supply tothe tooth. Position: It radiates in irregular fashion from cementum to bone at apical regionof socket.
Principal fibers of periodontal ligament 6.Interradicular group Functions: (i) Prevents luxation (ii) Prevents tooth tipping and torquing. Position: Found only between roots of multirooted tooth running from cementum into bone, forming crest of interradicular septum.
Sharpey’s fibers • The ends of the periodontal fibers that are embedded inalveolar bone and cementum are called Sharpey’s fibers. • On the cementum side these Sharpey’s fibers are much thinner in diameter and insert at closer intervals as compared with the alveolar bone side
cells of periodontal ligament
Ground Substance • It is an amorphous, nonfibrous and noncellular matrix which forms the major constituent of the periodontal ligament. • Ground substance helps in the transportation of water, electrolytes, nutrients and metabolites to and from the connective tissue cells, thus is essential for the maintenance of the normal function of connectivetissue. • It is thought to have a significant effect on thetooth’s ability to withstand stress loads.
functions of periodontal ligament
blood supply of periodontal ligament • The blood supply is derived from the inferior and superioralveolar arteries and reaches the periodontal ligament from 3sources: (i) Apical vessels (ii) Penetrating vessels from the alveolarbone (iii) Anastomosing vessels from the gingiva • They are present in the interstitial spaces of loose connective tissue between the principal fibres which runs longitudinally connected in the net like plexus closer to the bone than cementum. • The capillaries of periodontal ligament are fenestrated while in other connective tissues they are continuous. Due to fenestration, they have greater ability of diffusion and filtration which is related to high metabolic requirements of periodontal ligament and itshigh rate of turnover.

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PDL.pptx

  • 1. Periodontal Ligament PRESENTED BY DR ASIF K DEPARTMENT OF PERIODONTICS
  • 2. • Periodontal ligament is the soft, specialized connective tissue situated between the cementum covering the root of the tooth and bone forming the socket wall
  • 3. • Its width ranges from 0.15 to 0.38mm. • Periodontal ligament’s shape is like an hourglass apicocoronally. • Periodontal ligament is thinnest at the axis of rotation inthe middle and widens coronally and apically
  • 4. • As the crown approaches the oral mucosa during tooth eruption, the fibroblasts of dental follicle become active and start producing collagen fibrils. • These fibers initially lack orientation, but they soon acquire an orientation oblique to the tooth. • The first collagen bundles appear in the region immediately apical to the cementoenamel junction and give rise to the gingivodental fiber groups. • As tooth eruption progresses, additional oblique fibers appear and become attached to the newly formed cementum and bone. • The transseptal and alveolar crest fibers develop when the tooth merges into the oral cavity. • Alveolar bone deposition occurs simultaneously with periodontal ligament organization. Development
  • 5. • During eruption, cemental Sharpey’s fibers appear first, followed by Sharpey’s fibers emerging frombone. • Sharpey’s fibers of bone are fewer in number and more widely spaced than those emerging from the cementum. • At a later stage, alveolar fibers extend into the middle zone to join the lengthening cemental fibers and attain their classic orientation, thickness and strength when occlusal function is established.
  • 6. CONSTITUENTS • A. Periodontal ligament fibers • B. Cellular elements • C. Ground substances i. Glycosaminoglycans ii. Glycoproteins
  • 7. Periodontal Ligament Fibers • Mainly collagen and oxytalan fibres • Elastic fibers are present only in the wall of bloodvessels • Oxytalan are immature elastic fiber they support the blood vessels of periodontal ligament.
  • 8. Collagen • Types I, III,V, VI, XII of collagen are present in periodontal ligament • Collagen is synthesized by fibroblasts, chondroblasts,osteoblasts, odontoblasts and other cells • It is secreted in an inactive form called as procollagen  converted into tropocollagen polymerized into collagen fibrils aggregated into collagen bundles by the formation of crosslinkages. • There is rapid turnover rate of periodontal ligament collagen,with half life of only 10 – 15 days, which is about 5 times faster than gingival collagen.
  • 9. Principal fibers of periodontal ligament •1. Transseptal group Functions: • Reconstructed even after destruction of the alveolar bone has occurred in the periodontal disease. • Responsible for returning teeth to their original state after orthodontictherapy. Position: • Extends interproximally over alveolar bone crest and embedded in the cementum of adjacent teeth
  • 10. Principal fibers of periodontal ligament 2. Alveolar crest group • Functions: (i) Prevent extrusion (ii) Prevent lateral tooth movements • Position: Extends obliquely from the cementumjust beneath the junctional epithelium to the alveolar crest.
  • 11. Principal fibers of periodontal ligament 3. Horizontal group Position: Extends at right angles to the long axis of the tooth from cementum to alveolar bone.
  • 12. Principal fibers of periodontal ligament 4.Oblique group Functions: (i) Bear vertical masticatory stresses (ii) Transform vertical stress into tension on the alveolar bone. Position: Extends from the cementum in a coronal direction obliquely to the bone.
  • 13. Principal fibers of periodontal ligament 5.Apical group Functions: (i) Prevents tooth tipping (ii) Resists luxation (iii)Protects neurovascular supply tothe tooth. Position: It radiates in irregular fashion from cementum to bone at apical regionof socket.
  • 14. Principal fibers of periodontal ligament 6.Interradicular group Functions: (i) Prevents luxation (ii) Prevents tooth tipping and torquing. Position: Found only between roots of multirooted tooth running from cementum into bone, forming crest of interradicular septum.
  • 15. Sharpey’s fibers • The ends of the periodontal fibers that are embedded inalveolar bone and cementum are called Sharpey’s fibers. • On the cementum side these Sharpey’s fibers are much thinner in diameter and insert at closer intervals as compared with the alveolar bone side
  • 17. Ground Substance • It is an amorphous, nonfibrous and noncellular matrix which forms the major constituent of the periodontal ligament. • Ground substance helps in the transportation of water, electrolytes, nutrients and metabolites to and from the connective tissue cells, thus is essential for the maintenance of the normal function of connectivetissue. • It is thought to have a significant effect on thetooth’s ability to withstand stress loads.
  • 19. blood supply of periodontal ligament • The blood supply is derived from the inferior and superioralveolar arteries and reaches the periodontal ligament from 3sources: (i) Apical vessels (ii) Penetrating vessels from the alveolarbone (iii) Anastomosing vessels from the gingiva • They are present in the interstitial spaces of loose connective tissue between the principal fibres which runs longitudinally connected in the net like plexus closer to the bone than cementum. • The capillaries of periodontal ligament are fenestrated while in other connective tissues they are continuous. Due to fenestration, they have greater ability of diffusion and filtration which is related to high metabolic requirements of periodontal ligament and itshigh rate of turnover.