Cementum and Its Components Quiz
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Questions and Answers

What is the primary function of the interfibrillar matrix in cementum?

  • To provide structural support through collagen fibers.
  • To regulate vascularization within the cementum.
  • To facilitate cellular attachment of cementoblasts.
  • To mediate mineralization with hydroxyl apatite crystals. (correct)

Which cell type is primarily responsible for producing the interfibrillar matrix?

  • Ameloblasts
  • Odontoblasts
  • Fibroblasts
  • Cementoblasts (correct)

What is the primary origin of Sharpey's fibers found within the cementum?

  • Cementoblasts that differentiate along the cementum surface
  • Fibroblasts residing in the periodontal ligament (PDL) (correct)
  • Osteoblasts located within the alveolar bone
  • Epithelial cells of the junctional epithelium

What are the main components that constitute the interfibrillar matrix?

<p>Proteoglycans and glycoproteins. (C)</p> Signup and view all the answers

How are Sharpey's fibers typically oriented in relation to the cementodentinal junction (C.D.J.)?

<p>Perpendicular, or almost perpendicular, to the C.D.J. (A)</p> Signup and view all the answers

What is the process by which the interfibrillar matrix becomes mineralized?

<p>Precipitation of hydroxyl apatite crystals (D)</p> Signup and view all the answers

Which of the following is a characteristic feature of the extrinsic fiber system (E) in the cementum?

<p>It consists of Sharpey's fibers produced by PDL fibroblasts (A)</p> Signup and view all the answers

The classification of cementum is based on which attributes?

<p>The text only specifies that classification of cementum can be based on unspecified factors. (B)</p> Signup and view all the answers

What is the primary function of Sharpey's fibers within the cementum?

<p>To anchor the periodontal ligament to the tooth's root (D)</p> Signup and view all the answers

Where are the cell bodies of the cells that produce Sharpey's fibers located?

<p>Within the periodontal ligament. (A)</p> Signup and view all the answers

What is a notable characteristic of the cementodentinal junction in some deciduous teeth?

<p>It exhibits scalloped formations in certain cases. (C)</p> Signup and view all the answers

Which layer is situated between the cementum and dentin?

<p>The intermediate layer. (D)</p> Signup and view all the answers

What is the main function of the intermediate layer found between cementum and dentin?

<p>To function as a permeability barrier. (A)</p> Signup and view all the answers

How does the cementodentinal junction in deciduous teeth differ from that in permanent teeth?

<p>The deciduous junction can sometimes be scalloped. (D)</p> Signup and view all the answers

Besides acting as a permeability barrier, what is another potential role of the intermediate layer, based on its location?

<p>To facilitate structural adhesion between dentin and cementum (C)</p> Signup and view all the answers

Which of the following best describes the distribution pattern of hypercementosis?

<p>It can be localized to a single tooth, multiple teeth or generalized to the full dentition. (A)</p> Signup and view all the answers

What is the fundamental nature of hypercementosis in relation to cementum?

<p>An abnormal increase in thickness of cementum. (D)</p> Signup and view all the answers

In terms of anatomical scope, what is the most accurate way to describe the areas affected by hypercementosis?

<p>It can be present in just one tooth or a localized part of the tooth. (D)</p> Signup and view all the answers

When observing hypercementosis in a patient, what would be a plausible combination of locations it might affect?

<p>Multiple teeth in different quadrants plus part of one tooth in another quadrant. (C)</p> Signup and view all the answers

Which of the following defines the term circumscribed when used to describe hypercementosis?

<p>A pattern of thickening in cementum that is limited to specific, distinct locations or areas. (B)</p> Signup and view all the answers

What is a key characteristic of cementum in individuals with type 2 diabetes, according to the text?

<p>It is found to be thicker than in normal subjects. (D)</p> Signup and view all the answers

In the context of ankylosis, what process can lead to the fusion of bone and cementum?

<p>Abnormal cemental deposition. (B)</p> Signup and view all the answers

What impact does ankylosis have on the post-eruptive movements of a tooth?

<p>It prevents any post-eruptive movements. (A)</p> Signup and view all the answers

If a tooth demonstrates a complete lack of post-eruptive movement, which of the following conditions is most likely responsible?

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

Which of the following best defines the relationship between cementum and bone in cases of ankylosis?

<p>The two become fused together. (C)</p> Signup and view all the answers

What is the relationship between cementoid tissue and cementoblasts?

<p>Cementoblasts secrete the cementoid tissue. (B)</p> Signup and view all the answers

Which of the following best describes the location of cementoid tissue?

<p>The outermost surface of the cementum. (B)</p> Signup and view all the answers

What happens to cementoblasts after a layer of cementum reaches its full thickness?

<p>They enter a stage of reduced or stopped activity. (B)</p> Signup and view all the answers

How can the presence of cementoid tissue be used to understand the cementum?

<p>It highlights the areas where new cementum is being formed. (D)</p> Signup and view all the answers

What is the characteristic of cementoid tissue in relation to cementum formation?

<p>It is the precursor to the mineralised cementum. (B)</p> Signup and view all the answers

Flashcards

Cementocytes

Cells found within the cementum of the tooth, responsible for maintaining and repairing the cementum.

Cementocyte lacunae

The spaces within the cementum where cementocytes reside.

Sharpey's fibers

The fibrous structures that are embedded in the cementum and connect it to the periodontal ligament (PDL).

Extrinsic fiber system

The portion of the Sharpey's fibers that extends from the periodontal ligament into the cementum.

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C.D.J. (Cemento-Dentin Junction)

The boundary between the cementum and dentin.

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Interfibrillar matrix

A substance found within the cementum, composed of proteoglycans (complex sugars) and glycoproteins (proteins with sugar attachments), that is formed by cementoblasts (cells responsible for cementum production).

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Classification of cementum

Cementum can be categorized into different types based on recognizable characteristics.

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Cellular cementum

A type of cementum that is uniform and appears evenly distributed around the tooth root.

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Cellular cementum

A type of cementum characterized by the presence of cementocytes within the cementum. These cells are embedded in the cementum matrix and help in maintaining the cementum's health.

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Acellular cementum

A type of cementum that lacks cementocytes and is primarily found at the apex of the tooth root, near the tip.

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Cementodentinal Junction in Deciduous Teeth

The junction between cementum and dentin in deciduous teeth, which is sometimes shaped like a scallop.

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Intermediate Layer

A layer found between cementum and dentin.

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Function of the Intermediate Layer

The intermediate layer helps prevent the passage of materials between cementum and dentin.

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Cementum-Intermediate Layer-Dentin Structure

The cementum, intermediate layer, and dentin form a strong and resilient barrier.

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Cementodentinal Junction in Deciduous vs. Permanent Teeth

Deciduous teeth have a more irregular cementodentinal junction.

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What is hypercementosis?

Abnormal thickening of cementum, the layer covering the tooth root.

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How widespread is hypercementosis?

Hypercementosis can affect all teeth, a single tooth, or just parts of a tooth.

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What are the patterns of hypercementosis?

Hypercementosis can be diffuse, meaning affecting a larger area, or circumscribed, meaning limited to a specific area.

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Why consider hypercementosis in dental care?

It's important to consider the extent of hypercementosis when treating dental issues.

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Ankylosis

A condition in which joints become stiff and immobile due to abnormal bone fusion.

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Define hypercementosis

Hypercementosis is a condition where the protective cementum layer of the tooth root becomes abnormally thick.

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Cemento-dentinal junction

The deposition of cementum, a hard tissue that covers the root of a tooth.

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Abnormal cemental deposition

A condition where cementum (tooth root covering) abnormally sticks to bone, causing teeth to not move after eruption.

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Histology

The study of tissues under a microscope.

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Pathology

The study of the causes, development, and progression of diseases.

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Cementoid Tissue

A thin layer of newly formed cementum deposited on the surface of existing cementum.

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Cementoblasts

Specialized cells that produce and deposit cementoid tissue, forming new cementum.

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Quiescent Stage of Cementoblasts

Once cementum reaches its full thickness, cementoblasts become inactive and maintain the cementum.

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Apposition of Cementum

The process of adding new cementum layers to the root surface over time.

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Appositional Growth of Cementum

The formation of a new layer of cementoid tissue directly on top of the existing cementum, allowing for continuous growth.

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Study Notes

Cementum

  • Cementum is a specialized mineralized tissue that covers the tooth root and sometimes the crown
  • It is similar to bone, but has no blood vessels, lymph vessels, or innervation
  • It does not undergo resorption or remodeling, but continually deposits throughout life
  • Its main function is attaching collagen fibers of the periodontal ligament (PDL)

Physical Characteristics

  • Color: Light yellow, lighter than dentin, duller surface than enamel
  • Hardness: Less hard than dentin, contains fewer minerals
  • Thickness: Varies, thinnest at the cervix and thickest at the apex (20–50µm to 150–200µm)
  • Permeability: More permeable than dentin, permeability decreases with age

Chemical Composition

  • 45-50% inorganic hydroxyapatite by weight
  • 50-55% organic components: collagen and non-collagenous matrix proteins, with higher fluoride content
  • Organic component: Type I collagen and non-collagenous proteins
    • CAP (cementum-derived attachment protein) promoting mesenchymal cell attachment to the extracellular matrix
    • Rich in glucosaminoglycans like chondroitin sulphate, located around cementum lacunae

Cellular Elements

  • Cementoblasts: Line the root surface, active cells with numerous mitochondria, well-developed Golgi complex and an open-faced nucleus. Their function is forming cementoid, including intrinsic collagen fibers and interfibrillar matrix
  • Cementocytes: Located in lacunae, typically have numerous processes lying in canaliculi. Their processes are directed towards the tooth surface for nutrition of cementum (avascular tissue)

Fibrous Element

  • Extrinsic Fiber System (E): Sharpey's fibers, produced by fibroblasts in the PDL, oriented perpendicularly to the cemento-enamel junction (CEJ)
  • Intrinsic Fiber System (I): Produced by cementoblasts, fibers oriented parallel to the long axis of the root

Interfibrillar Matrix

  • Consists of proteoglycans and glycoproteins, undergo mineralization through precipitation of hydroxyl apatite crystals

Classification of Cementum

  • Based on cell presence/absence, fiber type (extrinsic/intrinsic), or a combination
    • Acellular cementum (primary): lacks cells
    • Cellular cementum (secondary): contains cells
    • Extrinsic fiber cementum (AEFC)
    • Intrinsic fiber cementum (CIFC)
    • Mixed cementum (CMFC or CMSC): combination of cell types and fiber types
    • Acellular afibrillar cementum (AAC): lacks cells and fibers

Cementodentinal Junction (CEJ)

  • Three types of junctions: overlap (60%), edge-to-edge (30%), gap (10%)
  • Overlap occurs due to degeneration of reduced enamel epithelium (R.E.E.) and allows dental sac cells to contact enamel and differentiate
  • Edge-to-edge: cementum and enamel meet at a sharp line
  • Gap: delay in root sheath separation at cervix, can result in hypersensitivity if gingiva recedes exposing dentin

Resorption and Repair

  • Resorption by multinucleated cementoclasts - Repair by cementoblasts
  • Presence of unmineralized collagen protects against resorption

Clinical Considerations

  • Hypercementosis: Abnormal thickening of cementum, may be diffuse or circumscribed
  • Hypertrophy: if overgrowth occurs in functional teeth, it improves functional qualities of the cementum, by providing more area for sharpey's fibers attachment.
  • Hyperplasia: if overgrowth occurs in nonfunctional teeth, can result in decreased number of sharpey's fibres, thus possibly affecting the anchorage.

Additional Points

  • Cementicles are calcified structures found in degenerated periodontal tissue or rests of Malsez; they can be free, attached, or embedded within cementum
  • Variations in cementum thickness have been observed in diabetic patients (potentially thicker in type 2 diabetics)
  • Ankylosis: abnormal cemental deposition that leads to bone-cementum fusion can result in lack of post-eruptive movement of the tooth.
  • Cemental caries can be found on exposed surfaces of cementum, associated with gingival recession, in older adults
  • Incremental lines in cementum are used in forensic dentistry to determine age

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Description

Test your knowledge about the structure and function of cementum, specifically focusing on the interfibrillar matrix and Sharpey's fibers. This quiz covers their origins, orientations, and mineralization processes. Ideal for dental students and professionals alike!

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