Dental Anatomy: Cementum Composition and Types

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Questions and Answers

What is the primary distinguishing characteristic of acellular afibrillar cementum (AAC)?

Located only in the cervical region (correct)

Found in the root region

Contains collagen fibers

Has significant functional importance

What is the main role of acellular extrinsic fibers cementum (AEFC)?

To provide nutrients to the tooth

To form a protective layer over dentine

For tooth support and anchorage (correct)

To assist with enamel formation

Which fibers are known to form the attachment with the periodontal ligament bundles?

Pulpal fibers

Cementoblast fibers

Sharpey’s fibers (correct)

Intrinsic fibers

Which type of cementum is known as secondary cementum?

Cellular cementum Signup and view all the answers

In which region of cellular cementum can you find unmineralized matrix or cementoid?

At the periphery of cellular cementum Signup and view all the answers

What type of fibers are primarily found in cellular cementum?

Intrinsic fibers Signup and view all the answers

What is the key function of cementum within the periodontium?

Supporting tooth position Signup and view all the answers

Which cells are responsible for the formation of cementum?

Cementoblasts Signup and view all the answers

How does cellular cementum differ from acellular cementum in regards to fiber composition?

Cellular cementum contains both intrinsic and extrinsic fibers Signup and view all the answers

Which of the following statements regarding acellular cementum is true?

It contains no cells. Signup and view all the answers

What is the main organic component of cementum?

Collagen fibers primarily type I Signup and view all the answers

Which type of cementum does not contain cells?

Acellular cementum Signup and view all the answers

What percentage of the root surface does acellular cementum cover?

40-70% Signup and view all the answers

Which type of fibers are primarily found in primary cementum?

Extrinsic collagen fibers (Sharpey's fibers) Signup and view all the answers

What is the critical pH level associated with cementum?

6.7 Signup and view all the answers

What type of structural feature is a characteristic of cellular cementum?

Mixed fiber type Signup and view all the answers

Which of the following statements is true about acellular cementum?

It is adjacent to the dentine at the dento-cementum junction. Signup and view all the answers

Which type of cementum is associated with increased formation after eruption?

Secondary cementum Signup and view all the answers

What is the role of non-collagenous matrix proteins in cementum?

They assist in mineralization. Signup and view all the answers

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

It aids in the healing process and maintains the width of the periodontal ligament. Signup and view all the answers

Where is acellular cementum predominantly located?

Towards the cervical region of the roots. Signup and view all the answers

What happens to the thickness and hardness of cementum as a person ages?

They increase progressively. Signup and view all the answers

What anatomical feature is connected to dentine hypersensitivity when exposed?

Cemento-Enamel Junction (CEJ). Signup and view all the answers

What is hypercementosis?

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

What percentage represents the overlap of cementum and enamel at the CEJ?

60-65% Signup and view all the answers

What is a common local factor that can contribute to hypercementosis?

Trauma Signup and view all the answers

In which teeth are heavier occlusal loads likely to necessitate thicker cementum?

Molar teeth. Signup and view all the answers

What describes a potential clinical implication of hypercementosis?

It can complicate tooth extractions. Signup and view all the answers

Functional repair of cellular cementum primarily helps in which aspect of periodontal health?

Healing periodontal diseases. Signup and view all the answers

The presence of which type of cementum is indicative of continuous cementogenesis throughout life?

Cellular cementum. Signup and view all the answers

Which of the following is considered a systemic factor that may lead to hypercementosis?

Paget's disease Signup and view all the answers

What impact does a gap at the CEJ have on dentine sensitivity?

It exposes dentine, increasing sensitivity. Signup and view all the answers

What is an idiopathic cause of hypercementosis?

An unknown cause Signup and view all the answers

Which of the following is NOT a characteristic of hypercementosis?

It leads to tooth sensitivity. Signup and view all the answers

In the context of hypercementosis imaging, which technique is NOT typically highlighted?

Ultrasound Signup and view all the answers

What type of cementum is characterized by the presence of both intrinsic and extrinsic fibers?

Cellular mixed stratified cementum (CMSC) Signup and view all the answers

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

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

What is a key function of cellular cementum?

It helps in the adaptation of the tooth root Signup and view all the answers

What do cementocytes originate from?

Cementoblasts Signup and view all the answers

Which of the following statements is true about the distribution of cellular cementum?

Cellular intrinsic fiber cementum is often absent in single-rooted teeth. Signup and view all the answers

What happens to cementum at the apex of the tooth over time?

It thickens to maintain occlusion. Signup and view all the answers

Which area of the tooth is likely to show the most significant thickening of cementum due to occlusal wear?

The apical region Signup and view all the answers

What cellular structure is embedded within cellular cementum?

Cementocytes Signup and view all the answers

What is the primary composition of cellular cementum that develops over time?

Intrinsic and extrinsic fibers Signup and view all the answers

What aspect of tooth movement does cellular cementum adapt to?

Movement due to extraction of teeth Signup and view all the answers

Study Notes

Cementum Composition

45-50% hydroxyapatite crystal
50-55% organic content
Collagen fibers mainly type I and minor quantities of types III, V, VI, XII, and XIV
Non-collagenous matrix proteins
Water

Cementum Types

Acellular cementum - Also known as primary cementum
- Covers the cervical and middle third of the root (40-70% of root surface)
- Forms slowly as the tooth erupts and continues post-eruption
- Contains collagen fibers (extrinsic) and non-collagenous matrix proteins
- No cells are present
Cellular cementum - Also known as secondary cementum
- Contains cementocytes
- Forms quickly compared to primary cementum
- Contains intrinsic fibers that are parallel to the root surface
- Over time, also contains extrinsic fibers

Acellular Cementum Sub-types

Acellular afibrillar cementum
- Found only in the cervical region, covering enamel and dentine
- Contains no collagen fibers
- No known functional significance
Acellular extrinsic fibers cementum
- The main type of acellular cementum
- Key function in support and anchorage

Cellular Cementum Cells

Cementoblasts
- Form cementum via cementogenesis
- Originate from the dental sac
Cementocytes
- Found in cellular cementum
- Originate from cementoblasts trapped in the matrix due to the speed of deposition

Cellular Cementum Sub-types

Cellular intrinsic fiber cementum
- Found in the apical third of the roots and inter-radicular regions of posterior teeth
- Often absent in single-rooted teeth
Cellular mixed stratified cementum
- Is a subcategory of CIFC containing both intrinsic and extrinsic fibers
- Over time this makes up the bulk of cellular cementum

Cellular Cementum Functions

Adaption to occlusal wear and tooth movement
- Reshaping of the root to adjust for movement of the tooth such as drifting when a tooth has been extracted
- Deposition of cementum at the apex to maintain occlusion and compensate for occlusal wear – thicker in posterior teeth (post-eruptive movement)
Repair
- Anatomical repair - Able to repair resorbed or fractured root surfaces to some degree
- Functional repair - Helps in periodontal disease healing by maintaining the width of the PDL

Cementum Lifecourse

Cementogenesis takes place continuously throughout life
The thickness, hardness and mineral content increases with age

Cemento-Enamel Junction

The relationship of the CEJ (where cementum and enamel meet) varies
- Overlap (60-65%)
- Gap (10%)
- Meet (25-30%)

Structural Abnormalities

Hypercementosis
- Excessive deposition of cementum towards the apex resulting in thicker roots
- Aetiology: Local factors (trauma or inflammation), Systemic factors (Paget's disease), Idiopathic (unknown)
- Clinical implications: May affect single or multiple teeth. Often asymptomatic. May cause problems for extractions.

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Description

Explore the composition and types of cementum, including acellular and cellular forms. This quiz covers the features, functions, and sub-types of cementum crucial for dental anatomy. Test your knowledge of this important dental tissue and its properties.