Cementum Composition and Types

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Questions and Answers

What percentage of the organic content in cementum is collagen fibers?

50-55% (correct)

70-75%

45-50%

60-65%

What is the critical pH of cementum?

6.7 (correct)

6.5

7.0

6.0

Which type of cementum is characterized by the presence of cells?

Primary cementum

Secondary cementum (correct)

Extrinsic cementum

Acellular cementum

Which type of fibers predominates in acellular cementum?

Extrinsic fibers Signup and view all the answers

What is the primary function of acellular cementum?

Acts as a primary attachment for periodontal fibers Signup and view all the answers

What covers 40-70% of the root surface in acellular cementum?

Cervical and middle third Signup and view all the answers

What type of cementum is formed by cementoblasts?

Secondary cementum Signup and view all the answers

What type of matrix proteins are present in cementum?

Both collagen and non-collagenous matrix proteins Signup and view all the answers

What is the primary function of cementum in relation to the periodontium?

To support the junction between the tooth root and alveolar bone Signup and view all the answers

Which of the following is NOT a type of cementum?

Fibrous cementum Signup and view all the answers

How is the structure of cementum related to its function?

Its cellular structure aids in the attachment of periodontal ligaments Signup and view all the answers

What clinical significance does an understanding of cementum have in health and disease?

It aids in diagnosing root caries and periodontal disease Signup and view all the answers

In comparison to enamel, dentine, and bone, cementum's primary composition is characterized by what?

Lower density than bone Signup and view all the answers

What is one of the primary functions of cementum?

To support the periodontal ligament Signup and view all the answers

Which type of cementum is formed after the tooth has emerged and is involved in repair?

Cellular cementum Signup and view all the answers

Which clinical implication is most commonly associated with hypercementosis?

Tooth mobility and possible extraction Signup and view all the answers

What structure does cementum primarily interface with at its apex?

Periodontal ligament Signup and view all the answers

What imaging technique is used for diagnosing conditions like hypercementosis?

Cone-beam computed tomography Signup and view all the answers

What natural process can affect the properties of cementum with age?

Increased mineralization Signup and view all the answers

What is the relationship between cementum and the dentin?

Cementum connects to the dentin at the cementodentin junction Signup and view all the answers

Which of the following is a characteristic of acellular cementum?

Formed primarily in the root area Signup and view all the answers

What is the origin of cementocytes?

They originate from cementoblasts trapped in the matrix. Signup and view all the answers

Where is cellular intrinsic fiber cementum (CIFC) primarily found?

In the apical third of the roots. Signup and view all the answers

Which of the following statements accurately describes cellular mixed stratified cementum (CMSC)?

It contains both intrinsic and extrinsic fibers. Signup and view all the answers

What role does cellular cementum play in relation to occlusal wear?

It reduces the height of enamel cusps over time. Signup and view all the answers

What is a key function of cellular cementum during tooth movement?

Allows for reshaping of the root. Signup and view all the answers

In which type of teeth is cellular intrinsic fiber cementum often absent?

In single-rooted teeth. Signup and view all the answers

How does cellular cementum contribute to maintaining tooth health after extraction?

It compensates for the movement of adjacent teeth. Signup and view all the answers

What condition leads to the deposition of cementum at the apex of teeth?

Post-eruptive movement of teeth. Signup and view all the answers

What is a characteristic of acellular afibrillar cementum (AAC)?

Found only in the cervical region Signup and view all the answers

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

Support and anchorage of the tooth Signup and view all the answers

What type of fibers are embedded in acellular cementum and are associated with the periodontal ligament?

Sharpey’s fibers Signup and view all the answers

Which of the following is true regarding cellular cementum?

Includes both cementocytes and cementoblasts Signup and view all the answers

What distinguishes cellular cementum from primary cementum?

Forms quickly and adapts to tooth growth Signup and view all the answers

Where is a layer of cementoid typically found in relation to cellular cementum?

At the periphery Signup and view all the answers

What role do fibroblasts play in the context of cementum?

Form Sharpey’s fibers Signup and view all the answers

What characteristic does intrinsic fibers in cellular cementum possess?

They are oriented parallel to the root surface Signup and view all the answers

Study Notes

Cementum Composition and Structure

Cementum is the thin layer of mineralized tissue that covers the root of a tooth
It is about 45-50% inorganic material (hydroxyapatite crystals), with a critical pH of 6.7
The remaining 50-55% of its composition is organic, consisting of collagen fibers (mainly Type I, with minor amounts of Type III, V, VI, XII, and XIV) and non-collagenous matrix proteins
Cementum is part of the periodontium, the tissues that support the teeth

Cementum Types and Distribution

There are two main types of cementum: acellular and cellular
Acellular cementum is the first type formed and covers the cervical and middle third of the root (40-70% of the root surface)
- It is further divided into two subtypes:
  - Acellular Afibrillar Cementum (AAC): This type is found only in the cervical region, covering enamel and dentine, and contains no collagen fibers. Its function is not fully understood.
  - Acellular Extrinsic Fibers Cementum (AEFC): The main type of acellular cementum, it plays a key role in support and anchorage.
Cellular cementum, also known as secondary cementum, is formed after acellular cementum.
- It is formed more rapidly and contains cementocytes (mature cementum cells)
- It is found in the apical third of the roots and in inter-radicular regions of posterior teeth
- Cellular cementum contains intrinsic fibers (parallel to the root surface), and over time, also contains extrinsic fibers.
- Cellular cementum is further subcategorized into:
  - Cellular Intrinsic Fiber Cementum (CIFC): predominantly found in the apical region of the roots and between the roots of molars.
  - Cellular Mixed Stratified Cementum (CMSC): a subcategory of CIFC, containing both intrinsic and extrinsic fibers, and makes up the bulk of cellular cementum over time.

Cementum Functions

Acellular Cementum: Primarily responsible for support and anchorage of the tooth within the alveolar socket.
- Extrinsic fibers within acellular cementum form the attachment with the periodontal ligament (PDL)
Cellular Cementum: Has a key function of adaptation, enabling:
- Reshaping of the root to accommodate tooth movement (like drifting after an extraction)
- Deposition of cementum at the apex to maintain occlusion and compensate for occlusal wear (particularly important in posterior teeth due to post-eruptive movement)

Clinical Significance

Cementum plays a vital role in the health and longevity of teeth.
It provides essential support and attachment for the tooth within the jaw, preventing its movement and loss.
- Damage or dysfunction of cementum can contribute to periodontal disease and root caries.

Summary

Composition: Cementum is composed of both inorganic (hydroxyapatite crystals) and organic material, including collagen fibers and non-collagenous matrix proteins.
Types: Two main types exist: acellular (primary) and cellular (secondary).
Functions: Cementum supports and anchors the tooth, and facilitates adaptation and reshaping of the root to accommodate tooth movement and wear.
Clinical Implications: Cementum plays a key role in the health and stability of teeth, and its integrity is critical for preventing periodontal disease and root caries.

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Description

Explore the intricate composition and structure of cementum, the mineralized tissue covering tooth roots. This quiz delves into the types of cementum, including acellular and cellular forms, and their significance in dental anatomy. Test your knowledge on the organic and inorganic components that make up this essential part of the periodontium.