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Periodontal ligament
 

Periodontal ligament

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    Periodontal ligament Periodontal ligament Presentation Transcript

    • Periodontal Ligament Dr. Syed Sadatullah Assistant Professor College of Dentistry King Khalid University Abha
    • Objectives At the end of this chapter the student should be able to understand the development process and histology of periodontal ligament. Sub topics Topic 1. Introduction Topic 2. Development of Periodontal Ligament Topic 2. Histology of Periodontal Ligament Dr.Syed Sadatullah King Khalid University . Abha
      • 1. Introduction
      • Periodontal ligament (PDL) is connective tissue that connects the cementum of the root to the alveolar bone proper, hence the name ligament
      • The thickness of the PDL varies from tooth to tooth and its position in relation to the root.
      • The thinnest portion of the PDL is near the middle of the root.
      • The width of PDL shows a progressive decrease with age.
      Dr.Syed Sadatullah King Khalid University . Abha
      • The PDL has a heterogeneous population of mesenchymal cells that when induced differentiate into fibroblasts, cementoblasts and osteoblasts
      • The fibroblasts also have the capacity to form PDL, Cementum and Alveolar bone any time in health.
      • The factors secreted by PDL fibroblasts inhibit mineralization and prevent ankylosis of the tooth.
      Dr.Syed Sadatullah King Khalid University . Abha
      • The PDL is always in a state of remodelling.
      • Functions of PDL
      • Formative
      • Supportive
      • Protective
      • Sensory
      • Nutritive
      Dr.Syed Sadatullah King Khalid University . Abha
      • 2. Development of PDL
      • 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
      Dr.Syed Sadatullah King Khalid University . Abha
      • Fibroblasts produce the periodontal ligament fibers.
      • They get embedded in the developing cementum and alveolar bone.
      • At first, all the developing fibers of the periodontal ligament run obliquely in a coronal direction from tooth to bone. This changes as the tooth erupts.
      • The part of PDL fibers present in the cementum and alveolar bone are called Sharpey’s fibers.
      Dr.Syed Sadatullah King Khalid University . Abha
    • Dr.Syed Sadatullah King Khalid University . Abha
    • Dr.Syed Sadatullah King Khalid University . Abha
    • Dr.Syed Sadatullah King Khalid University . Abha
      • 2 Histology of PDL
      • PDL like any other connective tissue is composed of cells and extracellular components
      • Cells
      • Fibroblasts
      • Cementoblasts
      • Osteoblasts
      • Osteoclasts
      • Undifferentiated mesenchymal cells
      • Epithelial cell rests of Malassez
      Dr.Syed Sadatullah King Khalid University . Abha
      • Extracellular components
      • Collageneous fibers
      • Elastic fibres
      • Ground substance
      • Nerves
      • Blood vessels
      • The main fibres are the principal fibres and additional fibres are oxytalan fibres
      Dr.Syed Sadatullah King Khalid University . Abha
      • 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
      Dr.Syed Sadatullah King Khalid University . Abha
      • Dentoalveolar fibre group
      • Alveolar crest group – near the cervical region
      • Horizontal fibre group – near the midroot
      • Oblique fibre group – immediately above apical group
      • Apical fibre group – near the apical area of the root
      • Interradicular group – between two roots
      Dr.Syed Sadatullah King Khalid University . Abha
    • Dr.Syed Sadatullah King Khalid University . Abha
      • Gingival fibre group
      • Dentogingival group – these fibres are the most numerous, extending from the cervical cementum to the lamina propria of the gingiva.
      • Alveologingival group – these fibres extend from the alveolar crest to the lamina propria of the gingiva.
      • Circular of Circumferential fibres– continuous around the neck of the tooth.
      • Transseptal fibres– these fibers extend from the cervical cementum of one tooth to the cervical cementum of the other.
      • Dentogingival group and alveologingival group fibers embed in attached gingiva and free gingiva, hence, also called attached gingival group and free gingival group fibers.
      Dr.Syed Sadatullah King Khalid University . Abha
      • Elastic 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.
      • Other elastic fibers are elastin and elaunin fibers.
      Dr.Syed Sadatullah King Khalid University . Abha
      • Vascular and Nerve supply
      • There are 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.
      Dr.Syed Sadatullah King Khalid University . Abha