LESSON 4: HISTOLOGICAL AND CLINICAL APPEARANCE OF CARIOUS LESION Flashcards
What is the basic structure of the normal enamel?
Enamel Rods or Enamel Prisms
Structures of Normal Enamel
Changes in these structures determine the lesions.
Enamel Rods/Prisms
Prism Borders
Striation
Incremental Growth Bands (Striae of Retzius)
Surface Zone
EPSIS
This is the earliest evidence of caries on a clean, dry teeth.
White spot (on the smooth surface)
These type of caries of the enamel can remineralize.
Non-cavitated caries
These lesions retain most of the original crystalline framework of the enamel rods and serves as nucleating agents for remineralization.
Non-cavitated enamel lesions
These ions from the saliva can penetrate the enamel surface and precipitate on the highly reactive crystalline surfaces of the enamel lesion.
Calcium and phosphate ions
During remineralization, this enhances the precipitation of calcium and phosphate, resulting in the remineralized enamel becoming more resistant to subsequent caries attack because of the incorporation of the more acid resistant fluorapatite.
Fluoride ions
These can be observed as intact, but discolored spots. These are usually brown or black. They should not be restored unless they are esthetically objectionable.
Clinically remineralized (arrested) lesions
These lesions can be initially detected as subtle breakdown of the enamel surface. They are sensitive to probing and can easily be enlarged by using sharp explorers and excessive probing force.
Cavitated enamel lesions
What are the 4 zones which can be seen microscopically in the enamel caries.
- Translucent Zone
- Dark Zone
- Body of the Lesion
- Surface of the Lesion
DBTS - Don’t Blame The Sids
The advancing front of the caries. the innermost zone.
Translucent Zone
Zone immediately above the translucent zone, appears dark and exhibits approx. 6% mineral loss per volume of enamel. Shows positive birefringence in polarized light (normal enamel negative birefringence).
Dark Zone
Zone that occupies the major portion of the lesion. It is the area of maximum demineralization. It is positively birefringent. This is the largest zone which exhibits enhanced striae of retzius.
Body of the Lesion
Zone that is approximately 20-100 um thick; thinner in active lesions and thicker in inactive ones. There is partial demineralization 10% mineral loss. The characteristic feature is the broadening of the prism sheaths.
Surface of the Lesion
This part of the teeth contains much less mineral and possesses microscopic tubules that provide a pathway for the ingress of bacteria and egress of minerals, and so less resistance to acid attack.
Dentin
When the carious lesion has penetrated the dentin, it spreads laterally along the ___________, undermining the enamel.
dentino-enamel junction (DEJ)
This is the patter of the incision in cross-section with a wide base at the DEJ and the apex directed pulpally.
V-shaped
As long as the pulp tissue is vital, this reacts to caries attack by attempting to initiate remineralization and blocking off the open dentinal tubules.
dentin-pulp complex
Infected dentin contains a wide-variety of pathogenic materials or irritants, including _______, _______, _______ and _______.
High acid levels, hydrolytic enzymes, bacteria and bacterial cellular debris.
The 3 levels of dentinal reaction to caries
- Reaction to long-term, low-level acid and demineralization associated with a slowly advancing lesion.
- Reaction to a moderate-intensity attack.
- Reaction to severe, rapidly advancing caries characterized by very high acid levels.
In slowly advancing caries, the vital pulp can repair demineralized dentin by remineralization of the ___________ and ___________.
intertubular dentin and apposition of peritubular dentin
SL - _____
DE - _____
ZD - _____
DT - _____
SZ - _____
AD - _____
TD - _____
SL- intact enamel layer surface
DE - demineralized enamel
ZD - zone of demineralization
DT - dead tracts
SZ - sclerotic zone
AD - affected dentin
TD - tertiary dentin
The pulp produces _________ and these cells produce reparative dentin on the affected portion of the pulp chamber wall.
replacement odontoblasts
High acid levels, hydrolytic enzymes, bacteria and bacterial cellular debris are the materials that cause:
1. ________
2. ________
- degeneration and death of the odontoblast and their tubular extensions
- mild inflammation of the pulp
CE - _____
ZP - _____
ZD - _____
DT - _____
SZ - _____
AD - _____
TD - _____
CE - cavitated enamel
ZP - zone of bacterial penetration
ZD - zone of demineralization
DT - dead tracts
SZ - sclerotic zone
AD - affected dentin
TD - tertiary dentin
Rapidly advancing caries bringing high acid levels overpowers the dentinal defenses and results in _______, _______, and _______ of the pulp.
infection, abscess, and death of the pulp.
Zones of Dentinal Caries
- Normal Dentin
- Tertiary Dentin
- Affected Dentin
- Dead Tracts
- Infected Dentin
The deepest area of the zone where the tubules with odontoblastic processes are smooth and no crystals are present in the lumens. No bacteria.
Normal Dentin
It has demineralization of the intertubular dentin and initial formation of fine crystals in the tubule lumen. There is damage to the odontoblastic process; no bacteria found (substransparent zone).
Affected Dentin
Affected Dentin is also known as _______.
Carious Inner Dentin
Zone of bacterial invasion marked by widening and distortion of the dentinal tubules, which are filled with bacteria, cannot remineralize, turbid dentin.
Infected Dentin
Consists of decomposed dentin teeming with bacteria: no recognizable dentin structure and collagen and minerals seem to be absent. Great number of bacteria are dispersed in this granular material and should be removed to prevent spreading the infection zone of destruction.
Infected Dentin
Infected Dentin is also known as __________.
Outer carious dentin
Caries that are usually seen where there is a gingival recession and the oral hygiene is poor.
Cementum Caries
Clinically, the cementum lesion appears as ___________ and ___________ in cross sections and progresses rapidly because of the lack of enamel covering.
saucer-shaped cavities and U-shaped
The microorganisms involved in root caries are chiefly __________ and they appear to invade the cementum either along Sharpey’s fibers between bundles of fibers comparable to invasion along dentinal tubules.
Actinomyces
Two Types of Cementum Caries
- Active Root Caries
- Arrested Root Caries
This specific response to the root caries is either partially or completely occluding the tubules partially or completely occluding the tubules with mineral crystals.
Sclerotic response
The carious lesion starts on the lateral walls of the fissures that eventually flare laterally at the bottom of the pit.
Pits and Fissure Caries
The carious lesion of pits and fissure caries follows the path of the ________; hence a characteristic angular ‘V’-shaped lesion is formed with the base towards the dentin and the apex towards the outer enamel surface.
enamel rod
Bacteria found in the pits and fissures of newly erupted teeth.
Gram positive cocci,
Streptococcus sanguis
Bacteria found in carious pits and fissures.
Streptococcus mutans
Smooth surfaces present a less favorable site for ____________. If this is attached, it is usually near gingiva or are under proximal contacts, which are protected sites for mechanical cleaning from the tongue, cheek movement and toothbrushing.
cariogenic biofilm attachment
Lesions starting on smooth surfaces have a broad area of origin and a conical, or pointed extension toward the DEJ. The ‘V-shaped’ pattern follows the direction of the enamel rods and are wide on enamel side tapering as it goes into the portion of the dentin, then spreads rapidly laterally and pulpally.
Smooth Surface Caries
Pits and fissure caries on enamel is an inverted V-shape or triangular where the base is on the _____ and the apex points outward in the _____.
Base - DEJ
Apex - Points outward in the enamel
Smooth surface caries on enamel is also a triangle or V -shaped, where the base is on the _____ and the apex is at the _____.
Base - enamel
Apex - DEJ
Pits and fissure caries rapidly spreads as it reaches the DEJ. It is also in a form of a triangle where the base is at the _____ and narrows to its apex toward the _____. It has a “base-to-base” relationship with the enamel caries.
Base - DEJ
Apex - Pulp
Smooth surface caries in the dentin likewise spreads laterally at the DEJ and narrows down as it reaches the pulp. It has an “_________” relationship with enamel caries.
apex-to-base
