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Questions and Answers
What is the primary factor that contributes to the demineralization of tooth surfaces leading to caries?
What is the primary factor that contributes to the demineralization of tooth surfaces leading to caries?
Which of the following describes the clinical appearance of dentine caries?
Which of the following describes the clinical appearance of dentine caries?
What is one of the four zones of destruction in dentine caries?
What is one of the four zones of destruction in dentine caries?
How does dentine protect itself and the pulp from carious assault?
How does dentine protect itself and the pulp from carious assault?
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What happens if the pH of the tooth surface does not neutralize after demineralization?
What happens if the pH of the tooth surface does not neutralize after demineralization?
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Which statement accurately describes the aetiology of dental caries?
Which statement accurately describes the aetiology of dental caries?
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What is the primary mineral that demineralizes during the caries process?
What is the primary mineral that demineralizes during the caries process?
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In the context of dental caries, what role does plaque bacteria play?
In the context of dental caries, what role does plaque bacteria play?
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Which of the following best describes the theme of the learning outcomes in this session?
Which of the following best describes the theme of the learning outcomes in this session?
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What characterizes the Zone of Demineralization?
What characterizes the Zone of Demineralization?
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Which statement about the Translucent (Sclerotic) Zone is true?
Which statement about the Translucent (Sclerotic) Zone is true?
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What type of secondary dentin is produced as a response to a strong irritant?
What type of secondary dentin is produced as a response to a strong irritant?
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Which characteristic is associated with tertiary dentin?
Which characteristic is associated with tertiary dentin?
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In the Zone of Demineralization, what indicates the area is still viable?
In the Zone of Demineralization, what indicates the area is still viable?
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What is the role of the calcification done by odontoblast processes in the Translucent Zone?
What is the role of the calcification done by odontoblast processes in the Translucent Zone?
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What is the purpose of the ICDAS system?
What is the purpose of the ICDAS system?
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What characterizes moderate stage caries as per ICDAS?
What characterizes moderate stage caries as per ICDAS?
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What is indicated by an ICDAS code of 6?
What is indicated by an ICDAS code of 6?
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Which of the following is a characteristic of extensive stage caries (ICDAS code 5)?
Which of the following is a characteristic of extensive stage caries (ICDAS code 5)?
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What type of material primarily composes dentine?
What type of material primarily composes dentine?
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What is the characteristic change observed in dentine during the progression of caries from enamel to dentine?
What is the characteristic change observed in dentine during the progression of caries from enamel to dentine?
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How does dentine contribute to its defense against caries?
How does dentine contribute to its defense against caries?
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What primarily causes the breakdown in crown integrity during enamel caries progression?
What primarily causes the breakdown in crown integrity during enamel caries progression?
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At what stage does ICDAS begin to show the caries process in detail?
At what stage does ICDAS begin to show the caries process in detail?
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Which ICDAS code is associated with a cavity that is clearly visible and demonstrates demineralization?
Which ICDAS code is associated with a cavity that is clearly visible and demonstrates demineralization?
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What is the appearance of heavily infected dentine when excavated?
What is the appearance of heavily infected dentine when excavated?
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Which ICDAS code corresponds to extensive cavities that indicate significant destruction of dentine?
Which ICDAS code corresponds to extensive cavities that indicate significant destruction of dentine?
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What contributes to the subjectivity in the ICDAS scoring system?
What contributes to the subjectivity in the ICDAS scoring system?
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What is NOT a symptom of moderate stage caries based on ICDAS criteria?
What is NOT a symptom of moderate stage caries based on ICDAS criteria?
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How can the softer dentine underneath the carious surface be identified in clinical practice?
How can the softer dentine underneath the carious surface be identified in clinical practice?
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What histological feature distinguishes microscopic dentine caries from enamel caries?
What histological feature distinguishes microscopic dentine caries from enamel caries?
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What is a significant consequence of bacterial destruction of dentine?
What is a significant consequence of bacterial destruction of dentine?
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What effect does caries have on the color of infected dentine?
What effect does caries have on the color of infected dentine?
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What is the primary indicator of carious dentine during clinical examination?
What is the primary indicator of carious dentine during clinical examination?
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As dentine becomes more damaged, what happens to the restoration treatment?
As dentine becomes more damaged, what happens to the restoration treatment?
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What characterizes the zone of destruction in infected dentine?
What characterizes the zone of destruction in infected dentine?
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Which of the following statements about affected dentine is true?
Which of the following statements about affected dentine is true?
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Which zone represents the area where bacterial acids have caused significant mineral loss?
Which zone represents the area where bacterial acids have caused significant mineral loss?
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What is a characteristic feature of the zone of penetration?
What is a characteristic feature of the zone of penetration?
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What can be concluded about the translucency observed in dentine?
What can be concluded about the translucency observed in dentine?
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What typically happens to the dentinal tubule structure in the zone of destruction?
What typically happens to the dentinal tubule structure in the zone of destruction?
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Which of the following describes the composition of the zone of destruction?
Which of the following describes the composition of the zone of destruction?
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Why is the zone of destruction not repairable?
Why is the zone of destruction not repairable?
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What distinguishes the zone of demineralization from the zone of destruction?
What distinguishes the zone of demineralization from the zone of destruction?
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What happens to the collagen matrix in the zone of destruction?
What happens to the collagen matrix in the zone of destruction?
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Study Notes
Histopathology of Enamel and Dentine Caries
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GDC Learning Outcomes:
- Describe oral diseases and their relevance to prevention, diagnosis, and treatment.
- Explain the aetiology and pathogenesis of oral disease.
- Describe relevant and appropriate dental, oral, craniofacial, and general anatomy; explain application to patient management.
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Pre-reading:
- Aetiology of Dental Caries lecture.
- Histology of enamel and dentine lectures.
Histopathology of Dentine Caries
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Learning Objectives:
- Describe the clinical appearance of dentine caries.
- Describe the histology of dentine caries.
- Identify and name the 4 zones of destruction in dentine caries.
- Identify mechanisms dentine uses to protect itself and the pulp.
Recap on Caries Aetiology
- As pH lowers, tooth surface (hydroxyapatite) demineralizes, breaking down into component ions.
- Continued demineralization (without neutralization) leads to caries.
ICDAS Scores
- International caries detection and assessment system for clinical research, practice, and epidemiology.
- A clinical scoring system for diagnosing caries.
- Enables caries process detection and characterization at different stages.
- Developed due to inconsistencies in previous caries diagnosis methods.
ICDAS Scores - Moderate Stage Caries
- Code 4: Dark shadow from dentin, with or without enamel breakdown.
- White or brown spot when wet.
- Darkened area of intrinsic shadow (grey, blue, brown).
ICDAS Scores - Extensive Stage Caries
- Code 5: Distinct cavity in opaque/discoloured enamel with visible dentin.
- Visible evidence of demineralization (white or brown walls).
- Code 6: Extensive cavity; visible extension into dentin.
Recap on the Structure of Dentine
- The mineral component of dentin is hydroxyapatite.
- Organic material is collagen.
- Dentin is a vital tissue with dentinal tubules permeated by odontoblast processes.
- Dentin is able to defend itself from assault (alongside the pulp).
Macroscopic Dentine Caries - ICDAS Code 4
- Progression from enamel to dentin shows change in substrate hardness.
- This causes lateral spread of caries under enamel.
- Leads to grey shadowing and eventual crown breakdown.
- Similar to cliff erosion with bacteria as water.
Macroscopic Dentine Caries - ICDAS Code 5/6
- Enamel undermining and breaking away leads to dentin exposure (ICDAS 5).
- This further leads to extensive cavities (ICDAS 6).
- More destruction equates to more difficulty in its restoration.
- Bacterial destruction makes dentin softer.
How does clinical appearance translate to histological appearance?
- Clinical observation corresponds to microscopic appearance.
Microscopic Dentine Caries
- Caries progress along the dentin (deeper).
- 'Undercutting' of enamel with caries progresses.
- Microscopic observations reveal zones.
Microscopic Dentine Caries
- Zones (dentinal-lesion cross sections) are: necrotic, contaminated, demineralized, translucent, tertiary, and hard dentin.
Microscopic Dentine Caries (Affected vs. Infected Zones)
- Affected dentin: changing but without bacteria.
- Infected dentin: penetrated bacteria resulting in destruction.
Zone 1 - Zone of Destruction
- Outermost, necrotic; clinically dark brown, soft, and mushy.
- Rapid caries: soft yellow; slow caries: browner.
- Mineral content dissociated by bacterial acid; collagen denatured.
- High bacterial load, with dentinal tubule destruction and liquefaction foci.
- Transverse clefts are formed.
Zone 1 - Zone of Destruction
- Cannot be repaired.
- Weak surface for bonding.
- Poor sealing ability.
- Inadequate restoration support.
Zone 2 - Zone of Penetration/Bacterial Invasion
- Dentinal tubule structure still exists.
- Tubules invaded by bacteria that decalcify through acid.
- Dissolving proteins.
- Believed this zone is to be removed (with bur).
Zone 3 - Zone of Demineralization
- Acid spread from upper zones to un-occluded dentinal tubules; demineralizing dentin.
- No bacteria present.
- This is the advancing lesion front (very small, <1 mm).
Zone 3 - Zone of Demineralization
- Can feel softer than sound dentin.
- Can be repaired by the dentin pulp complex.
- Paler brown in appearance.
Zone 4 - Translucent (Sclerotic) Zone
- Acid penetration initiates odontoblast process calcification.
- Tubules 'plugged' with mineral; slows acid/toxin penetration.
- Radiographically: whiter area below caries (hyper mineralization).
- Does not have to be removed.
Zone 5 - Tertiary Dentine
- Formed away from the lesion (not a zone though).
- New dentin laid down along pulp-dentin border.
- This increases dentine between lesion & pulp for pulp protection.
Zone 5 - Tertiary Dentine
- Produced when pulp inflammation (by advancing acid).
- Irregular tubular structure with types.
- Reactionary (mild irritant): deposited by surviving odontoblasts.
- Reparative (strong irritant): deposited after odontoblast death or cell death.
Zone 5 -Tertiary Dentine
- Diagram showing mechanisms of formation with mild/intense injury and corresponding dentine types.
Video for Review
- This video summarizes the process. Please view from 4:40.
- [YouTube link].
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Description
This quiz explores the histopathology of enamel and dentine caries, focusing on their clinical appearance and the histological changes that occur. You'll learn about the zones of destruction within dentine caries and the protective mechanisms employed by dentine. Prepare to enhance your understanding of oral disease and its management.
