Histology of cementum medium

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Questions and Answers

What is one of the primary functions of cementum?

Fluid transport

Anchorage (correct)

Sensory perception

Energy production

How does cementum typically change over time?

Becomes less hard

Ceases to grow

Increases in thickness (correct)

Decreases in mineral content

What is a notable characteristic of cementum's cellular structure?

It is entirely acellular in adults

It has multiple fiber types (correct)

It does not regenerate

It contains only organic material

What implication does the relationship between the cementoenamel junction (CEJ) and cementum have?

It can vary and impact dental health Signup and view all the answers

Which aspect of cementum is highlighted in relation to clinical implications?

It alters significantly during periodontal disease Signup and view all the answers

What is the critical pH at which hydroxyapatite crystals can start to dissolve?

6.7 Signup and view all the answers

What is the primary type of collagen found in the organic content of cementum?

Type I collagen Signup and view all the answers

Which characteristic is associated with acellular cementum?

Is primarily composed of Sharpey's fibers Signup and view all the answers

How much of the root surface does acellular cementum cover?

40-70% Signup and view all the answers

What marks the junction where acellular cementum meets dentine?

Dento-cementum junction Signup and view all the answers

Which type of cementum continues to form throughout the lifecycle of the tooth?

Secondary cementum Signup and view all the answers

What is the main characteristic of afibrilar cementum?

Lacks both intrinsic and extrinsic fibers Signup and view all the answers

Which component is NOT typically found in the organic content of cementum?

Type IV collagen Signup and view all the answers

What is the primary function of acellular extrinsic fibers cementum (AEFC)?

Provides support and anchorage Signup and view all the answers

Where is acellular afibrillar cementum (AAC) primarily located?

Only in the cervical region Signup and view all the answers

What type of fibers are primarily found in cellular cementum?

Intrinsic fibers Signup and view all the answers

Which component forms the attachment between cementum and the periodontal ligament?

Sharpey’s fibers Signup and view all the answers

What describes the characteristics of acellular afibrillar cementum (AAC)?

Contains no collagen fibers Signup and view all the answers

Which type of cementum forms more rapidly than primary cementum?

Cellular cementum Signup and view all the answers

What is cemetogenesis?

Formation of cementum by cementoblasts Signup and view all the answers

What substance may be found at the periphery of cellular cementum?

Cementoid Signup and view all the answers

Which of the following statements about acellular cementum is true?

It has no known functional significance. Signup and view all the answers

What is the orientation of extrinsic fibers in acellular extrinsic fibers cementum?

Perpendicular to the root surface Signup and view all the answers

What are cementocytes derived from?

Cementoblasts trapped in the matrix Signup and view all the answers

In which area is cellular intrinsic fiber cementum primarily found?

Apical third of the roots and inter-radicular regions of posterior teeth Signup and view all the answers

What is the primary function of cellular cementum?

Adapting shape to adjust for tooth movement and occlusion Signup and view all the answers

Which type of cellular cementum contains both intrinsic and extrinsic fibers?

Cellular mixed stratified cementum Signup and view all the answers

Why is cellular cementum thicker in posterior teeth?

To compensate for greater functional wear from occlusion Signup and view all the answers

Which of the following statements about cellular intrinsic fiber cementum is false?

It is generally more abundant in anterior teeth. Signup and view all the answers

What is one of the roles of deposits of cementum at the apex of teeth?

To compensate for occlusal wear Signup and view all the answers

Cellular cementum is least likely to be found in which type of tooth?

Single-rooted teeth Signup and view all the answers

What structure embeds cementocytes in cellular cementum?

Cytoplasmic processes Signup and view all the answers

What is the primary role of cellular cementum in relation to periodontal disease?

It helps in the healing process of periodontal disease. Signup and view all the answers

Where is acellular cementum primarily located in relation to the tooth structure?

Cervical region of the roots. Signup and view all the answers

Which factor is NOT associated with hypercementosis?

Excessive fluoride exposure. Signup and view all the answers

How does cementum thickness change with age?

It increases in thickness and hardness. Signup and view all the answers

What percentage of the CEJ is characterized by 'overlap' among teeth?

60-65% Signup and view all the answers

What occurs during anatomical repair of cellular cementum?

Repair of resorbed or fractured root surfaces. Signup and view all the answers

What is hypercementosis primarily characterized by?

Excessive deposition of cementum towards the apex. Signup and view all the answers

The distribution of cementum in teeth is affected by which factor?

Occlusal loads experienced by the teeth. Signup and view all the answers

What is the consequence of cementum continuously forming throughout life?

Increase in thickness and hardness over time. Signup and view all the answers

What is a common clinical implication of hypercementosis?

Extraction of affected teeth may become complicated. Signup and view all the answers

Study Notes

Composition

Cementum is composed of two main components: inorganic material (45-50%) and organic material (50-55%)
Hydroxyapatite crystals make up the inorganic portion of cementum.
Cementum begins to dissolve at a critical pH of 6.7
Collagen fibers are the primary component of the organic material.
Types I, III, V, VI, XII, and XIV collagen fibers are found in cementum.
Non-collagenous matrix proteins and water also contribute to cementum's organic content.

Structural Features

Cementum is classified based on cell presence and fiber type.
Acellular cementum lacks cells and is typically formed first (primary cementum).
Cellular cementum contains cementocytes and is formed later (secondary cementum).
Extrinsic fibers are connected to the periodontal ligament (PDL) and alveolar bone.
Intrinsic fibers are embedded within the cementum and run parallel to the root surface.
Acellular afibrillar cementum (AAC) contains no collagen fibers and is found in the cervical region.
Acellular extrinsic fibers cementum (AEFC) is the most common type of acellular cementum.
Cellular intrinsic fiber cementum (CIFC) is found in the apical third of roots and interradicular regions.
Cellular mixed stratified cementum (CMSC) contains both intrinsic and extrinsic fibers.

Acellular Cementum: Functions and Location

Acellular cementum primarily functions in support and anchorage.
Extrinsic fibers embed into cementum and alveolar bone, creating Sharpey's fibers that contribute to tooth anchorage.
Acellular cementum is mainly concentrated in the cervical and middle third of the root, covering 40-70% of the root surface.

Cellular Cementum: Functions and Location

Cellular cementum forms quickly compared to acellular cementum.
This process involves cementoblasts, which originate from the dental sac and form cementum through cementogenesis.
Cementoblasts become trapped in the matrix, transforming into cementocytes.
Cementoid, an unmineralized matrix, is present at the periphery of cellular cementum.
Intrinsic fibers are parallel to the root surface and may be joined by extrinsic fibers over time.
Cellular cementum is primarily located in the apical third of the root and interradicular regions.

Cellular Cementum Functions: Adaption and Repair

Cellular cementum allows for adaption and repair of the root surface in response to changing needs.
This includes reshaping the root for tooth movement and deposition of cementum at the apex to compensate for occlusal wear.
Cellular cementum can also repair resorbed or fractured root surfaces.

Distribution of Cementum

There is a distinct pattern of cementum distribution along the root:
- Acellular cementum (AEFC) predominates in the cervical region.
- Cellular cementum (CMSC and CIFC) dominates in the apical region.
Cementum thickness varies based on the type of tooth and its location within the mouth.

Cementum over the Lifecourse

Cementogenesis continues throughout life.
Cementum thickens, hardens, and increases in mineral content with age.

Cemento-Enamel Junction (CEJ)

The CEJ, where cementum and enamel meet, can have different relationships:
- Overlap (most common): cementum covers enamel.
- Gap: a space exists between cementum and enamel.
- Meet: cementum and enamel are juxtaposed.

Structural Abnormalities - Hypercementosis

Hypercementosis, an excessive deposition of cementum at the apex, can result in thicker roots.
Possible causes include local factors (trauma or inflammation) and systemic factors (Paget's disease) or unknown causes.
Clinical implications:
- Can affect single or multiple teeth.
- May cause problems during tooth extraction.

Summary

Acellular and cellular cementum differ in cell presence and fiber types, contributing to distinct functions.
Functions of Cementum:
- Anchorage and support
- Adaptation
- Repair
Clinical Implications:
- Continued growth and deposition throughout life
- Variations in CEJ relationships
- Potential for abnormalities such as hypercementosis

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Description

This quiz explores the composition and structural features of cementum, focusing on its inorganic and organic components, types of collagen fibers, and the classifications based on cell presence and fiber type. Understand the differences between acellular and cellular cementum and their roles in dental anatomy.