Histopathology Dentine Caries medium

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Questions and Answers

What happens to tooth enamel as the pH decreases in the presence of plaque bacteria?

Enamel becomes harder and more resistant to decay.

Enamel undergoes mineralization and strengthens.

Enamel starts to demineralize into its component ions. (correct)

Enamel remains unchanged regardless of pH levels.

Which of the following is NOT one of the zones of destruction in dentine caries?

Dark zone

Translucent zone

Sclerotic zone (correct)

Infected zone

What is the primary mechanism through which dentine protects itself from caries?

Initiating inflammation to expel bacteria.

Depositing tertiary dentine in response to injury. (correct)

Promoting rapid decay of surrounding tissues.

Undergoing complete demineralization to prevent further damage.

What role do fermentable carbohydrates play in the development of caries?

They serve as a food source for plaque bacteria, lowering pH. Signup and view all the answers

What describes the characteristics of the Zone of Destruction?

It is the outermost area and is necrotic. Signup and view all the answers

What type of dentine is found in the Zone of Penetration?

Infected dentine with intact tubules. Signup and view all the answers

Which of the following is TRUE about the Zone of Destruction?

There is a significant denaturation of the collagen matrix. Signup and view all the answers

What is a feature of the bacteria found in the Zone of Destruction?

They produce enzymes that denature the collagen matrix. Signup and view all the answers

What does the presence of liquefaction foci indicate?

Destruction of dentinal tubule structures. Signup and view all the answers

What causes the lateral spread of caries underneath enamel?

The change in hardness of the substrate from enamel to dentine Signup and view all the answers

In which zone is the dentine still salvageable, although infected?

Zone of Penetration. Signup and view all the answers

What clinical sign indicates that dentine has become exposed due to caries?

Enamel cavitation Signup and view all the answers

What is the consequence of bacterial destruction in dentine?

Soften dentine due to demineralization Signup and view all the answers

What is a consequence of having a poor surface to bond in the Zone of Destruction?

Reduced resistance to fracture. Signup and view all the answers

What is typically required for the treatment of the Zone of Destruction?

Removal of infected dentine with an excavator. Signup and view all the answers

Which of the following statements is true regarding ICDAS Code 5/6 caries?

They indicate severe damage with extensive cavity formation Signup and view all the answers

What effect does the undermining of enamel have on its structural integrity?

It leads to enamel becoming fragile and prone to breaking away Signup and view all the answers

What should be avoided when probing an area with possible caries?

Using a sharp probe on the cavity Signup and view all the answers

What color typically indicates heavily infected dentine during examination?

Brown Signup and view all the answers

What is the relationship between caries progression and the integrity of the crown?

Caries progression leads to breakdown in crown integrity Signup and view all the answers

What is the shape associated with microscopic dentine caries?

Mushroom shape Signup and view all the answers

Which zone of the carious lesion represents the area of destruction at the outer surface?

Zone of destruction Signup and view all the answers

How does the progression of caries compare between enamel and dentine?

Caries progress faster in dentine than in enamel Signup and view all the answers

What differentiates affected dentine from infected dentine?

Affected dentine lacks bacteria, infected contains bacteria Signup and view all the answers

Which of the following zones is noted as tertiary dentine located away from the lesion?

Normal dentine Signup and view all the answers

What is a characteristic feature of the entry point for microscopic dentine caries?

Small entrance in enamel that expands into dentine Signup and view all the answers

What byproducts do bacteria produce that can affect dentine during the carious process?

Acids and toxins Signup and view all the answers

Which zone represents caries-affected dentine that shows changes from being healthy?

Zone of demineralization Signup and view all the answers

What is the characteristic feature of the Zone of Demineralization?

Absence of bacteria and starting dentine destruction Signup and view all the answers

Which of the following statements about the Translucent (Sclerotic) Zone is correct?

It indicates a protective reaction with hyper-mineralization. Signup and view all the answers

What is true about Tertiary Dentine?

It creates additional dentine for pulp protection. Signup and view all the answers

Which factor characterizes Affected Dentine in Zone 3?

It may feel softer compared to sound dentine. Signup and view all the answers

What is the primary function of the Tertiary Dentine?

To create a barrier against pulp irritation. Signup and view all the answers

What is one of the characteristics of the Zone of Demineralization?

It can be repaired by the dentine pulp complex. Signup and view all the answers

What differentiates reactionary dentine from reparative dentine?

Reparative dentine originates from dying odontoblasts. Signup and view all the answers

Which potential appearance indicates the Translucent (Sclerotic) Zone on X-ray?

A whiter area due to hyper-mineralization. Signup and view all the answers

What happens to the odontoblast processes in the Translucent Zone?

They become hyper-mineralized and plugged. Signup and view all the answers

In Zone 5, what type of irritant is associated with reparative dentine?

Severe irritants causing cell death. Signup and view all the answers

What is the purpose of the ICDAS scoring system?

To identify the caries process at various stages Signup and view all the answers

What is indicated by a dark shadow from dentine showing through enamel?

Moderate stage caries with potential enamel breakdown Signup and view all the answers

Which ICDAS score indicates extensive stage caries?

Code 6 Signup and view all the answers

What are the common color indicators for early demineralization suggested by ICDAS?

White or brown spots when wet Signup and view all the answers

How can moderate stage caries be visually identified?

By a distinct cavity with visible dentine exposure Signup and view all the answers

What does the demineralization process in dentine involve?

Visible evidence of white or brown walls Signup and view all the answers

What structure of dentine assists in its ability to defend itself from carious assaults?

Dentin tubules and odontoblasts Signup and view all the answers

What is the significance of white patches appearing around a lesion?

Start of demineralization process Signup and view all the answers

Which option represents a more advanced stage of caries as defined in ICDAS?

Code 5, with visible evidence of demineralization Signup and view all the answers

What is a clinical sign of extensive stage caries as per ICDAS?

A large cavity with visible dentine exposure Signup and view all the answers

Study Notes

Histopathology of Enamel and Dentine Caries

The presentation covers the histopathology of enamel and dentine caries.
Learning outcomes include describing oral diseases and their relevance to prevention, diagnosis, and treatment.
Learning outcomes include explaining the etiology and pathogenesis of oral disease.
Learning outcomes include describing relevant dental, oral, craniofacial, and general anatomy and explaining their application to patient management.

Pre-reading

The pre-reading material includes the aetiology of dental caries lecture.
Factors discussed are time, susceptible tooth surface, fermentable carbohydrates, and plaque bacteria.

Histology of Enamel and Dentine

The lecture notes cover the histology of enamel and dentine, as a pre-reading assignment.

Histopathology of Dentine Caries

The histopathology of dentine caries is a primary focus.

Learning Objectives

By the end of the session, attendees will be able to describe the clinical appearance of dentine caries, and describe the histology of dentine caries.
Attendees will be able to identify the four zones of destruction in dentine caries.
Attendees will be able to identify mechanisms used by dentine to protect itself and the pulp from assault.

Recap on Caries Aetiology

As pH decreases, the tooth surface demineralizes, breaking down into component ions.
Continued demineralisation, without neutralization, leads to caries.
Hydroxyapatite is the mineral component of tooth enamel.

ICDAS Scores

ICDAS is an international caries detection and assessment system used in clinical research, practice, and epidemiological studies.
It allows for the diagnosis and staging of caries.
The system provides detailed characterization of the carious activity of lesions.
Inconsistency in diagnosis was a driving factor in the development of the system.

Moderate Stage Caries (ICDAS Code 4)

Dark shadow from dentine can be seen within the enamel.
White or brown spots appear when wet, and/or darkened intrinsic shadowing.
The dark shadowing shows underneath the enamel.
Code 4 indicates an underlying dark shadow, from dentin.

Extensive Stage Caries (ICDAS Code 5/6)

A distinct cavity appears with visible dentine in opaque or discolored enamel.
Visible evidence of demineralization (white or brown walls)
For Code 5 there is cavitation with visible dentine
Code 6 represents an extensive cavity with visible dentine extension.

Recap on the Structure of Dentine

Dentine's mineral component is hydroxyapatite.
The organic material is collagen.
Dentinal tubules permeate the tissue and connect to odontoblasts.
Dentine protects the pulp.
The dentinal-pulp complex highlights the interdependent nature of these tissues.

Macroscopic Dentine Caries- ICDAS Code 4

Progression from enamel to dentine demonstrates changing hardness in the substrate.
This causes lateral spread of caries under the enamel, leading to grey shadowing.
Breakdown in crown integrity can result.
Erosion of the cliff-like tooth structure is analogous to bacteria-induced erosion.

Macroscopic Dentine Caries- ICDAS Code 5/6

Enamel further undermining leads to dentine exposure.
This results in an extensive cavity (ICDAS 5), ultimately becoming an extensive cavity (ICDAS 6).
The level of destruction increases the difficulty of restoration.

Bacterial destruction makes the dentine softer.

Identifying infected dentine involves a sharp probe.
Avoiding damaging the fragile enamel is a primary concern.
Removing infected dentine using an excavator often reveals a browner colour.
The hard dentine lies beneath the infected area.

How does this clinical appearance translate to histological appearance?

The translation of clinical findings into histological descriptions is a critical aspect of the study.

Microscopic Dentine Caries

Caries progress through enamel into dentine by 'undercutting', forming a mushroom-shaped lesion.
This is different from enamel caries which shows different patterns.

Microscopic Dentine Caries- Zones of Destruction, Penetration, Demineralisation

A detailed cross-section illustrates zones, such as the demineralization zone, and zones of penetration and destruction. There are 6 zones in the dentine including the necrotic zone, contaminated zone, demineralized zone, translucent zone, tertiary dentine and normal dentine.
The microscopic analysis reveals the various stages of caries progression within the dentine.
Different levels of caries destruction are evident across the cross-section.

Affected vs Infected Dentine

Bacteria invasion of dentine leads to destruction ("infected").
Early stages of change, without bacteria ("affected"), are evident from the change in the dentine.

Zone 1 - Zone of Destruction

This zone is clinically characterized as dark brown, soft, and mushy. It is irreparable, and typically quickly removed.
It lacks the mineral content.
Collagen matrix is damaged by the proteolytic enzymes released by bacteria.
The bacterial load is high.
Dentinal tubules are destroyed.
Liquefaction foci are characteristic.

Zone 2 - Zone of Penetration/Bacterial Invasion

Dentinal tubules remain intact.
Dentine is decalcified and proteins are dissolved.
This intermediate layer of caries requires removal.

Zone 3 - Zone of Demineralisation

Acid spreads through un-occluded dentinal tubules.
Demineralization occurs, potentially resulting in a 'softer' feel.
No bacteria are present in this area.
This zone is the active front of the lesion and may be small (less than 1 mm).

Zone 4 - Translucent (Sclerotic) Zone

Acid penetration triggers odontoblast response to increase calcification.
This zone aims to slow acid and toxin penetration and protect the pulp.
Radiographically appears as a whiter area beneath the cavity.

Zone 5 - Tertiary Dentine

This is new dentine formed in response to pulp inflammation.
There is new dentine laid down at the pulp-dentine border, away from the caries itself.
This aims to protect the pulp.
There are two types of reactionary dentine - a milder and more intense response, related to the degree or irritant.

Video for Review

A video summarizing the process is available at the given link, starting from timestamp 4:40.

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Description

This quiz covers the histopathology of enamel and dentine caries, focusing on their relevance to oral diseases, diagnosis, and treatment. Participants will explore the etiology, pathogenesis, and histology related to dental caries, enhancing their understanding of patient management.