Histology of PDL hard
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Questions and Answers

What is the primary function of the alveolar crest group fibers?

  • Resist lateral tipping movements of the tooth
  • Support the tooth against vertical masticatory forces
  • Prevent extrusion of the tooth from the socket (correct)
  • Prevent rotation of the tooth in the socket

    • Where do the oblique group fibers primarily insert?

  • Into the inter-radicular septum
  • At right angles to the tooth's long axis
  • Into the alveolar bone in a coronal direction (correct)
  • Into the apex of the tooth

    • What is the primary functional role of the periodontal ligament?

  • To form the main component of the tooth enamel
  • To serve as a barrier against bacterial infection
  • To connect the tooth root to the surrounding bone (correct)
  • To provide structural support to the gums

    • How does the periodontal ligament communicate with the bone's vascular system?

    <p>Via vascular channels in the bone</p> Signup and view all the answers

    What happens to the apical group fibers in incompletely formed roots?

    <p>They are absent or not found</p> Signup and view all the answers

    Which group fibers are crucial for connecting neighboring teeth?

    <p>Gingival fiber group</p> Signup and view all the answers

    What is a significant characteristic of the periodontal ligament?

    <p>It has a rich blood supply and sensory innervation</p> Signup and view all the answers

    In which area does the periodontal ligament merge with the dental pulp?

    <p>At the root apex</p> Signup and view all the answers

    What is a common age-related change observed in the periodontal ligament (PDL)?

    <p>Decrease in the number of fibroblasts and cells</p> Signup and view all the answers

    Which of the following best describes the development aspect of the periodontal ligament?

    <p>It is part of the overall tooth development process</p> Signup and view all the answers

    What contributes to the sensory functions of the periodontal ligament?

    <p>Innervation by nerve fibers</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the periodontal ligament?

    <p>It is primarily epithelial in nature</p> Signup and view all the answers

    What is a key cellular component found in the periodontal ligament?

    <p>Fibroblasts</p> Signup and view all the answers

    What is the initial characteristic of collagen fibers in the periodontal ligament before they become organized?

    <p>They lack organization.</p> Signup and view all the answers

    What fibers appear first during the eruption process of the periodontal ligament?

    <p>Cemental Sharpey's fibers.</p> Signup and view all the answers

    Which cells are primarily responsible for forming collagen in the periodontal ligament?

    <p>Fibroblasts.</p> Signup and view all the answers

    How do alveolar fibers contribute to the periodontal ligament?

    <p>They join lengthening cemental fibers.</p> Signup and view all the answers

    What is the role of progenitor cells within the periodontal ligament?

    <p>They replace dying cells.</p> Signup and view all the answers

    Which types of cells are involved in the resorption process within the periodontal ligament?

    <p>Osteoclasts and cementoclasts.</p> Signup and view all the answers

    What is the primary blood supply to the periodontal ligament?

    <p>Inferior and superior alveolar arteries.</p> Signup and view all the answers

    What are the Epithelial Rests of Malassez remnants from?

    <p>Epithelial root sheath.</p> Signup and view all the answers

    During the development of the periodontal ligament, how do the fibers become thicker and stronger?

    <p>When they are in occlusal function.</p> Signup and view all the answers

    What role does the periodontal ligament (PDL) play in relation to the tooth?

    <p>Attaches the tooth to the alveolar bone</p> Signup and view all the answers

    How does the width of the PDL change under heavy loading conditions near the crest of the alveolus?

    <p>Narrowing to 0.14mm</p> Signup and view all the answers

    Which property of the periodontal ligament contributes to its ability to serve as a shock absorber?

    <p>Ability to transmit occlusal forces</p> Signup and view all the answers

    What is the average width of the periodontal ligament in millimeters?

    <p>0.20mm</p> Signup and view all the answers

    What happens to the periodontal ligament when there is no functional loading on the tooth?

    <p>It becomes narrower</p> Signup and view all the answers

    What is a primary function of the rich blood supply in the periodontal ligament?

    <p>Providing a source of nutrition</p> Signup and view all the answers

    What type of forces does the periodontal ligament transmit during mastication?

    <p>Oclusal forces</p> Signup and view all the answers

    In which conditions is the periodontal ligament likely to be the widest?

    <p>When subjected to heavy loading</p> Signup and view all the answers

    Which process related to the periodontal ligament allows for healing and adaptation?

    <p>Deposition</p> Signup and view all the answers

    Which histological structure is associated with the periodontal ligament on radiographs?

    <p>Periodontal space</p> Signup and view all the answers

    Which type of vessels are responsible for linking periodontal structures?

    <p>Anastomosing vessels from the gingiva</p> Signup and view all the answers

    What primary function do the principal fibres of the periodontal ligament serve?

    <p>Distribute forces of mastication and speech</p> Signup and view all the answers

    Which cranial nerve is associated with the sensory nerve supply to the periodontal ligament?

    <p>Fifth cranial nerve</p> Signup and view all the answers

    What happens to blood supply in the periodontal ligament with smoking?

    <p>It may impact blood supply negatively</p> Signup and view all the answers

    What is the composition of the fibers found in the periodontal ligament?

    <p>Collagen</p> Signup and view all the answers

    Which principal fiber group in the periodontal ligament is closest to the alveolar crest?

    <p>Alveolar crest group</p> Signup and view all the answers

    Where is the periodontal ligament typically widest?

    <p>At the cervical margin and apex</p> Signup and view all the answers

    Which of the following statements about the nervous supply to periodontal ligaments is true?

    <p>The sensory nerves are responsible for touch, pressure, and pain.</p> Signup and view all the answers

    What do Sharpey’s fibres connect within the periodontal ligament?

    <p>Bone to cementum</p> Signup and view all the answers

    Which of the following is NOT a principal fibre group of the periodontal ligament?

    <p>Transversal group</p> Signup and view all the answers

    Study Notes

    Periodontal Ligament

    • Connective tissue surrounding tooth root and connecting it to the alveolar bone
    • Continuous with gingival connective tissue and communicates with bone marrow spaces
    • Merges with dental pulp at the root apex
    • Contains a rich blood supply and is very sensory

    Functions of the Periodontal Ligament

    • Sensory: Rich nerve fibers transmit touch, pressure, temperature and pain
    • Physical: Attaches the tooth to the alveolar bone, maintains tooth position, transmits occlusal forces to bone, acts as a shock absorber
    • Nutritive: Rich blood supply provides nutrition for cells, supports formation and resorption
    • Formative & Resorptive: High cell turnover, facilitates bone and cementum formation and resorption

    Periodontal Ligament Width

    • Average width of the PDL is 0.2mm (range 0.15mm to 0.38mm)
    • Width varies with loading conditions:
      • Heavy loaded: Wider at the crest and fundus of the alveolus
      • Normally loaded: Narrower at the crest and fundus of the alveolus
      • Functionless: Narrowest at the crest and fundus of the alveolus
    • The PDL adapts to pressure and loading conditions, becoming wider and more noticeable on radiographs

    Radiographic Appearance

    • The PDL appears as the periodontal space on radiographs
    • It is a radiolucent area between the lamina dura of the alveolar bone proper and radiopaque cementum
    • The periodontal space is narrower in permanent teeth than deciduous teeth

    Development

    • The PDL develops from the dental follicle after root development begins.
    • Fibroblasts in the follicle produce collagen.
    • Initial fibers lack organization and become oblique to the tooth.
    • The first fibers are apical to the cementoenamel junction (CEJ) and give rise to gingivodental fibers.
    • As eruption progresses, more fibers develop and become attached to new cementum and bone.
    • Cemental Sharpey's fibers appear first, followed by Sharpey's fibers in the bone.
    • After eruption, alveolar fibers extend into the middle zone to join the lengthening cemental fibers, gaining thickness and strength during occlusal function.

    Structural Elements

    • Cells:
      • Formative: Osteoblasts, fibroblasts, cementoblasts
      • Resorptive: Osteoclasts, cementoclasts, fibroblasts
      • Progenitor: Undifferentiated mesenchymal cells, replacing dying cells
      • Defense: Mast cells, macrophages
    • Epithelial Rests of Malassez: Epithelial cells found near the cemental side of the PDL, remnants of Hertwig's epithelial root sheath
    • Extracellular Substance:
      • Fibers: Collagen fibers (mainly)
      • Ground Substance: Water, collagen fibers, tissue fluid pressure high (10mmHg above atmospheric pressure)

    Blood Supply

    • Main blood supply originates from:
      • Superior and inferior alveolar arteries
      • Penetrating vessels from the alveolar bone
      • Anastomosing vessels from the gingiva

    Nerve Supply

    • Two types of nerves:
      • Sensory: Touch, pressure, pain
      • Autonomic: Associated with PDL vessels
    • Branches of the second and third division of the 5th cranial nerve (trigeminal nerve)

    Principal Fiber Groups

    • All fibers are made of collagen and are organized into groups according to orientation and function.
    • Functions include distributing forces of mastication and speech.
    • Principal fibers are embedded into cementum and bone, known as Sharpey's fibers.
    • Main groups include:
      • Alveolar Crest Group: Prevents tooth extrusion, resists lateral, tilting, and intrusive forces
      • Horizontal Group: Resists horizontal and tipping forces
      • Oblique Group: Resists vertical masticatory forces, prevents tooth intrusion
      • Apical Group: Resists vertical, luxative, and twisting forces, protects nerves and vessels at the apex
      • Interradicular Group: Resists vertical and lateral movement, tipping, torquing, and luxation

    Interdental Ligament (Transseptal Fibers)

    • Important fibers that run through the gingival mucosa to connect neighboring teeth
    • Insert interdentally into cervical cementum of neighboring teeth over the alveolar crest
    • Resist rotational forces and keep teeth in alignment
    • Maintain gingival integrity

    Gingival Fiber Group

    • Separate but adjacent fiber groups within the lamina propria of the marginal gingiva

    Ground Substance Functions

    • Exchange of metabolites
    • Ion and water binding
    • Fibre orientation
    • Tooth support and binding mechanisms
    • Removal of toxins and nutrient delivery

    Age Changes

    • Decrease in cells
    • Increase in fibrous tissue
    • Decrease in vascularity and mitotic activity
    • Narrowing of PDL width
    • Scalloping seen on calcified tissues (bone, cementum)

    Clinical Considerations

    • Understanding PDL function is crucial for dental practice.
    • Considerations include:
      • Preventing damage to the PDL during procedures
      • Understanding how changes in PDL structure affect tooth movement and stability
      • Recognizing signs of PDL damage in periodontal disease

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    Histology Of Periodontal Ligament GN PDF 2021

    Description

    This quiz covers the essential aspects of the periodontal ligament, including its anatomy, functions, and characteristics. Explore how the periodontal ligament connects teeth to the alveolar bone and its role in sensory perception and nutrient supply. Learn about the average width of the PDL and how it varies under different loading conditions.

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