Histology of Human Cementum
45 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the relationship between the thickness of the cellular cementum (CMSC) and the masticatory stress experienced by a tooth?

  • CMSC thickness is directly proportional to the masticatory stress, with thicker CMSC in teeth with greater masticatory stress.
  • CMSC thickness is directly proportional to the masticatory stress, but only in pre-functional molars.
  • CMSC thickness is not directly related to masticatory stress, but may reflect the past history of tooth eruption. (correct)
  • CMSC thickness is inversely proportional to the masticatory stress, with thinner CMSC in teeth with greater masticatory stress.

    • What is the primary function of the alternating lamellae in the cellular cementum (CMSC)?

  • To facilitate the growth of the root.
  • To provide anchorage for the tooth.
  • To resist multi-directional masticatory stresses. (correct)
  • To protect the tooth from bacteria.

    • What is the primary type of cementum found at the root tip during the initial stages of root development?

  • Acellular intrinsic fiber cementum (AIFC)
  • Cellular intrinsic fiber cementum (CIFC)
  • Acellular extrinsic fiber cementum (AEFC) (correct)
  • Cellular cementum (CMSC)

    • Which of the following is NOT a glycosaminoglycan found in the extracellular matrix of cementum?

    <p>Hyaluronic acid (C)</p> Signup and view all the answers

    How do the small proteoglycans (decorin, biglycan, and lumican) differ from the large proteoglycan versican?

    <p>Small proteoglycans are only found in cellular cementum, while versican is found in both cellular and acellular cementum. (A)</p> Signup and view all the answers

    Which type of cementum is primarily responsible for tooth anchorage?

    <p>Acellular extrinsic fiber cementum (AEFC) (C)</p> Signup and view all the answers

    What is the role of Hertwig's epithelial root sheath in cementogenesis?

    <p>It guides the differentiation of dental papilla cells into odontoblasts. (B)</p> Signup and view all the answers

    Why are there limited studies on human cementogenesis?

    <p>There are ethical concerns related to studying human tooth development. (C)</p> Signup and view all the answers

    What is the primary subject of the studied processes in the rat molars?

    <p>Mineralization during acellular cementogenesis (B)</p> Signup and view all the answers

    Which method was employed to study the lamellar structure of cementum?

    <p>Scanning electron microscopy and contact microradiography (D)</p> Signup and view all the answers

    What role does Hertwig’s epithelial root sheath play in rat molar cementogenesis?

    <p>Undergoes cell proliferation and death (A)</p> Signup and view all the answers

    What is one of the findings related to Hertwig’s epithelial root sheath cells?

    <p>They do not transform into cementoblasts. (C)</p> Signup and view all the answers

    What aspect of the periodontium is mentioned in relation to apoptosis?

    <p>Early developing periodontium of rat molars (D)</p> Signup and view all the answers

    What is the role of cementoblasts in the context of principal fibers (PF)?

    <p>They encircle intrinsic fibers (IF) with wing-like processes. (C)</p> Signup and view all the answers

    Which process is suggested to explain the reduction in cell numbers during cementogenesis?

    <p>Apoptosis in epithelial cell rests of Malassez. (D)</p> Signup and view all the answers

    What characterizes the intrinsic fibers (IF) in relation to extrinsic fibers (EF)?

    <p>IF encircle EF within the cementum. (C)</p> Signup and view all the answers

    What happens to the wing-like processes of cementoblasts as they can progress with cementogenesis?

    <p>They retract and transform into finger-like processes. (D)</p> Signup and view all the answers

    In what cellular structure does apoptosis occur, according to the recent studies discussed?

    <p>Epithelial cell rests of Malassez. (D)</p> Signup and view all the answers

    What happens during Hertwig’s epithelial root sheath disintegration?

    <p>Epithelial cells undergo programmed cell death. (B)</p> Signup and view all the answers

    What provides support to the principal fibers (PF) in histological occurrences?

    <p>Intrinsic fibers (IF) in cementum. (C)</p> Signup and view all the answers

    What is the teleological significance of apoptosis in the context of cementogenesis?

    <p>To regulate the balance of cellular components. (A)</p> Signup and view all the answers

    What hypothesis has almost surpassed the classical mesenchymal hypothesis regarding the transdifferentiation of epithelial sheath cells?

    <p>The alternative epithelial hypothesis (A)</p> Signup and view all the answers

    In which decades did the alternative epithelial hypothesis gain attention due to experiments involving rats and mice?

    <p>1980s and 1990s (C)</p> Signup and view all the answers

    What phenomenon does epithelial-mesenchymal transition (EMT) describe?

    <p>The transition of epithelial cells into cementoblasts (D)</p> Signup and view all the answers

    Why has the alternative epithelial hypothesis gained more support than the classical mesenchymal hypothesis?

    <p>It accounts for the decrease in epithelial sheath cells. (B)</p> Signup and view all the answers

    What event is described as a normal occurrence in embryos during development?

    <p>Epithelial-mesenchymal transition (EMT) (D)</p> Signup and view all the answers

    Who first proposed the alternative epithelial hypothesis?

    <p>Thomas (B)</p> Signup and view all the answers

    What is indicated by the decrease in epithelial sheath cells during disintegration?

    <p>A conversion to cementoblasts may be happening (B)</p> Signup and view all the answers

    Which of the following statements is true regarding extrinsic and intrinsic fibers?

    <p>Intrinsic fibers encircle extrinsic fibers in CIFC. (D)</p> Signup and view all the answers

    What differentiates cellular cementum from acellular cementum?

    <p>Presence of cementsocytes (B), Thickness of the cementum (C)</p> Signup and view all the answers

    Which classification includes both intrinsic and extrinsic fibers?

    <p>Cellular mixed stratified cementum (D)</p> Signup and view all the answers

    What type of cementum is typically found covering the cervical root?

    <p>Acellular extrinsic fiber cementum (D)</p> Signup and view all the answers

    Which type of cementum is characterized by the presence of intensely hematoxylin-stainable lines?

    <p>Cellular mixed stratified cementum (A)</p> Signup and view all the answers

    What is an essential feature of cellular mixed stratified cementum?

    <p>It is partitioned by incremental lines. (D)</p> Signup and view all the answers

    What are the main types of fibers found in cementum?

    <p>Intrinsic and extrinsic fibers (D)</p> Signup and view all the answers

    Which type of cementum is best described as a sub-variety of cellular intrinsic fiber cementum?

    <p>Cellular mixed stratified cementum (B)</p> Signup and view all the answers

    Who established the current classification widely used in dentistry?

    <p>Schroeder (B)</p> Signup and view all the answers

    What usually forms as the first cementum in the genesis of cellular mixed stratified cementum (CMSC)?

    <p>Extrinsic fiber-free CIFC (B)</p> Signup and view all the answers

    Which statement reflects current understanding regarding occlusal stimuli and CIFC genesis?

    <p>The influence of occlusal stimuli on CIFC genesis is unclear. (C)</p> Signup and view all the answers

    At what developmental stage do cementoblasts appear and start producing the cementum matrix?

    <p>Immediately following epithelial sheath detachment (A)</p> Signup and view all the answers

    What mode of matrix production do cementoblasts undergo during the initial CIFC formation?

    <p>Multipolar mode (C)</p> Signup and view all the answers

    What type of collagen fibril arrangement characterizes the initial CIFC?

    <p>Randomly arranged (C)</p> Signup and view all the answers

    Which of the following statements is true regarding cementoblasts during CIFC deposition?

    <p>Some cementoblasts show concaves on their surface. (B)</p> Signup and view all the answers

    Which structure is responsible for the initial deposition of CIFC?

    <p>Cementoblasts on unmineralized dentin (A)</p> Signup and view all the answers

    What is recognized as precementum during CIFC formation?

    <p>Unmineralized cementum matrix (B)</p> Signup and view all the answers

    Flashcards

    Cementum Classification

    Cementum is classified into cellular and acellular based on the presence of cementocytes.

    Cellular Intrinsic Fiber Cementum (CIFC)

    CIFC contains intrinsic fibers and cementocytes, forming part of cellular cementum.

    Cellular Mixed Stratified Cementum (CMSC)

    CMSC includes both cellular cementum and stratified fibers, distinct in its structure.

    Acellular Extrinsic Fiber Cementum (AEFC)

    AEFC is a thin layer covering cervical root surfaces in teeth, lacks cementocytes.

    Signup and view all the flashcards

    Extrinsic Fibers

    Extrinsic fibers (Sharpey's fibers) are embedded in the cementum and secreted by fibroblasts.

    Signup and view all the flashcards

    Intrinsic Fibers

    Intrinsic fibers are secreted solely by cementoblasts, found in some cementum types.

    Signup and view all the flashcards

    Incremental Lines in Cementum

    Incremental lines are visible partitions in cementum, indicating growth patterns.

    Signup and view all the flashcards

    Function of Cementoblasts

    Cementoblasts are cells that produce cementum and intrinsic fibers in the root structure.

    Signup and view all the flashcards

    Acellular Cementum

    A type of cementum that does not contain cells and is mainly composed of collagen fibers.

    Signup and view all the flashcards

    Mineralization

    The process where minerals are deposited in organic tissue, increasing its hardness and strength.

    Signup and view all the flashcards

    Hertwig’s Epithelial Root Sheath

    A structure that plays a crucial role in tooth root formation but does not transform into cementoblasts.

    Signup and view all the flashcards

    Cementoblasts

    Cells responsible for forming cementum, the hard tissue covering the tooth root.

    Signup and view all the flashcards

    Apoptosis in Periodontium

    Programmed cell death occurring in the early development of the supporting tissues around teeth.

    Signup and view all the flashcards

    Principal fibers (PF)

    The main collagen fibers in the periodontal ligament.

    Signup and view all the flashcards

    Intrinsic fibers (IF)

    Fibers secreted by cementoblasts that encircle the extrinsic fibers.

    Signup and view all the flashcards

    Extrinsic fibers (EF)

    Fibers originating from the periodontal ligament.

    Signup and view all the flashcards

    Cementogenesis

    The process of cementum formation.

    Signup and view all the flashcards

    Apoptosis

    The process of programmed cell death.

    Signup and view all the flashcards

    Epithelial Rests of Malassez

    Clusters of epithelial cells in the periodontal ligament.

    Signup and view all the flashcards

    Hertwig's epithelial root sheath

    A structure that influences root development in teeth.

    Signup and view all the flashcards

    Classical mesenchymal hypothesis

    A theory stating that mesenchymal cells play a crucial role in differentiation in dental tissues.

    Signup and view all the flashcards

    Epithelial-mesenchymal transition (EMT)

    The process by which epithelial cells transform into cell types with mesenchymal features.

    Signup and view all the flashcards

    Alternative epithelial hypothesis

    A newer hypothesis suggesting that some epithelial sheath cells can differentiate into cementoblasts via EMT.

    Signup and view all the flashcards

    Epithelial sheath

    A structure made up of epithelial cells that plays a role during tooth development.

    Signup and view all the flashcards

    Palatogenesis

    The developmental process of forming the palate in the embryo involving EMT.

    Signup and view all the flashcards

    Cellular Mixed Stratified Cementum (CMSC)

    A type of cementum formed by cementoblasts, containing layers with different cellular structures.

    Signup and view all the flashcards

    Cementum Interfacial Fibers (CIFC)

    The first cementum layer that forms during the genesis of CMSC, considered crucial but not fully understood.

    Signup and view all the flashcards

    Cementum Matrix

    The organic framework secreted by cementoblasts that eventually mineralizes to form cementum.

    Signup and view all the flashcards

    Predentin

    A layer of unmineralized dentin that acts as a base for cementum deposition.

    Signup and view all the flashcards

    Multipolar Mode

    The mode of matrix production where cementoblasts create collagen fibrils in multiple directions.

    Signup and view all the flashcards

    Unipolar Mode

    The mode of matrix production involving cementoblasts producing collagen fibers in a single direction.

    Signup and view all the flashcards

    Precementum

    The unmineralized matrix produced by cementoblasts before it becomes mineralized cementum.

    Signup and view all the flashcards

    Glycosaminoglycans

    Large polysaccharides that are covalently attached to core proteins in proteoglycans.

    Signup and view all the flashcards

    Types of proteoglycans

    Versican is large and decorin, biglycan, and lumican are small proteoglycans.

    Signup and view all the flashcards

    Cementum thickness

    CMSC is thicker in molars to withstand masticatory stress.

    Signup and view all the flashcards

    Schroeder's observation

    CMSC distribution may reflect tooth eruption history rather than just function.

    Signup and view all the flashcards

    Masticatory stresses

    Forces exerted on teeth during chewing.

    Signup and view all the flashcards

    Study Notes

    Histology of Human Cementum

    • Cementum is a mineralized tissue covering tooth roots, supporting teeth in alveolar sockets.
    • It's distinct from bone, being avascular and not undergoing dynamic remodeling.
    • Early microscopy demonstrated cementum.
    • Data on human cementum histology has been limited due to comparison with rodent studies which can be unreliable.
    • Cementum is classified into cellular and acellular types (based on presence/absence of cementocytes).

    Classification of Cementum

    • Acellular Extrinsic Fiber Cementum (AEFC):
      • Primarily at the cervical root, thin
      • Composed of densely packed extrinsic fibers (Sharpey's fibers)
      • No cementocytes
    • Cellular Intrinsic Fiber Cementum (CIFC):
      • Usually a component of CMSC
      • Contains intrinsic fibers and cementocytes
      • Density of extrinsic fibers varies (e.g., rich, poor, free)
    • Cellular Mixed Stratified Cementum (CMSC):
      • Predominantly found in apical and interradicular regions
      • Thicker in molars than incisors
      • Consists of stratified CIFC, frequently with AEFC inclusions marked by incremental lines.
    • Acellular Afibrillar Cementum (AAC):
      • Patchy, found at the cemento-enamel junction.
      • No collagen or cementocytes
      • Origin of AAC still uncertain; three potential origins proposed.
    • Intermediate Cementum:
      • Positioned between dentin and CMSC
      • Its origin is controversial; either a part of dentin or enamel-like tissue.
      • Research points to it being part of dentin, with features that might be related to the periodontal ligament.

    Structure of Cementum

    • AEFC:
      • Covers cervical root surfaces
      • Extrinsic fibers densely packed, nearly perpendicular to root surfaces
      • Incremental lines (highly mineralized lines mark rests in AEFC formation).
    • CIFC:
      • Contains intrinsic fibers and cementocytes
      • Fibers vary in extrinsic fiber density
    • CMSC:
      • Stratified, contains alternating incremental lines
      • Various types of CIFC based on extrinsic fiber density (e.g., rich, poor, free).

    Composition of Organic Matrix

    • Primarily collagen (types I and III in bovine cementum, type I primarily in human)
    • Non-collagenous proteins (e.g., bone sialoprotein, osteopontin)

    Function of Cementum

    • Primary function is tooth support
    • AEFC is suitable for anchorage
    • CIFC assists in adaptation and reshaping during tooth movement.
    • The alternating lamellae within CIFC might help resist masticatory forces

    Development of Cementum

    • Mechanisms of AEFC and CMSC formation are examined in detail in stages.
    • Cementoblasts, which secrete collagen fibers, are key
    • Initial matrix formation, mineralization, and fiber arrangement in both AEFC and CMSC are traced.

    Origin of Cementoblasts

    • Predominantly from mesenchymal dental follicle (classical mesenchymal hypothesis)
    • An alternative hypothesis proposes epithelial sheath cells can transform into cementoblasts through an epithelial-mesenchymal transition (EMT). Current research favors the classical view concerning cementoblast origin.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Histology of Human Cementum: Structure, Function, and Development (2016) PDF

    Description

    Explore the histology of human cementum, a mineralized tissue crucial for tooth support. Learn about its distinct types, including acellular and cellular forms, and their unique characteristics. This quiz delves into foundational knowledge essential for understanding dental anatomy and tissue function.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser