LESSON 4: HISTOLOGICAL AND CLINICAL APPEARANCE OF CARIOUS LESION

Question 1

What is the basic structure of the normal enamel?

Answer 1

Enamel Rods or Enamel Prisms

Question 2

Structures of Normal Enamel

Changes in these structures determine the lesions.

Answer 2

Enamel Rods/Prisms
Prism Borders
Striation
Incremental Growth Bands (Striae of Retzius)
Surface Zone

EPSIS

Question 3

This is the earliest evidence of caries on a clean, dry teeth.

Answer 3

White spot (on the smooth surface)

Question 4

These type of caries of the enamel can remineralize.

Answer 4

Non-cavitated caries

Question 5

These lesions retain most of the original crystalline framework of the enamel rods and serves as nucleating agents for remineralization.

Answer 5

Non-cavitated enamel lesions

Question 6

These ions from the saliva can penetrate the enamel surface and precipitate on the highly reactive crystalline surfaces of the enamel lesion.

Answer 6

Calcium and phosphate ions

Question 7

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.

Answer 7

Fluoride ions

Question 8

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.

Answer 8

Clinically remineralized (arrested) lesions

Question 8

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.

Answer 8

Cavitated enamel lesions

Question 9

What are the 4 zones which can be seen microscopically in the enamel caries.

Answer 9

1. Translucent Zone
2. Dark Zone
3. Body of the Lesion
4. Surface of the Lesion

DBTS - Don’t Blame The Sids

Question 9

The advancing front of the caries. the innermost zone.

Answer 9

Translucent Zone

Question 10

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).

Answer 10

Dark Zone

Question 11

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.

Answer 11

Body of the Lesion

Question 12

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.

Answer 12

Surface of the Lesion

Question 13

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.

Answer 13

Dentin

Question 14

When the carious lesion has penetrated the dentin, it spreads laterally along the ___________, undermining the enamel.

Answer 14

dentino-enamel junction (DEJ)

Question 15

This is the patter of the incision in cross-section with a wide base at the DEJ and the apex directed pulpally.

Answer 15

V-shaped

Question 15

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.

Answer 15

dentin-pulp complex

Question 15

Infected dentin contains a wide-variety of pathogenic materials or irritants, including _______, _______, _______ and _______.

Answer 15

High acid levels, hydrolytic enzymes, bacteria and bacterial cellular debris.

Question 15

The 3 levels of dentinal reaction to caries

Answer 15

1. Reaction to long-term, low-level acid and demineralization associated with a slowly advancing lesion.
2. Reaction to a moderate-intensity attack.
3. Reaction to severe, rapidly advancing caries characterized by very high acid levels.

Question 16

In slowly advancing caries, the vital pulp can repair demineralized dentin by remineralization of the ___________ and ___________.

Answer 16

intertubular dentin and apposition of peritubular dentin

Question 16

SL - _____
DE - _____
ZD - _____
DT - _____
SZ - _____
AD - _____
TD - _____

Answer 16

SL- intact enamel layer surface
DE - demineralized enamel
ZD - zone of demineralization
DT - dead tracts
SZ - sclerotic zone
AD - affected dentin
TD - tertiary dentin

Question 16

The pulp produces _________ and these cells produce reparative dentin on the affected portion of the pulp chamber wall.

Answer 16

replacement odontoblasts

Question 16

High acid levels, hydrolytic enzymes, bacteria and bacterial cellular debris are the materials that cause:
1. ________
2. ________

Answer 16

1. degeneration and death of the odontoblast and their tubular extensions
2. mild inflammation of the pulp

Question 17

CE - _____
ZP - _____
ZD - _____
DT - _____
SZ - _____
AD - _____
TD - _____

Answer 17

CE - cavitated enamel
ZP - zone of bacterial penetration
ZD - zone of demineralization
DT - dead tracts
SZ - sclerotic zone
AD - affected dentin
TD - tertiary dentin

Question 19

Rapidly advancing caries bringing high acid levels overpowers the dentinal defenses and results in _______, _______, and _______ of the pulp.

Answer 19

infection, abscess, and death of the pulp.

Question 19

Zones of Dentinal Caries

Answer 19

1. Normal Dentin
2. Tertiary Dentin
3. Affected Dentin
4. Dead Tracts
5. Infected Dentin

Question 20

The deepest area of the zone where the tubules with odontoblastic processes are smooth and no crystals are present in the lumens. No bacteria.

Answer 20

Normal Dentin

Question 21

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).

Answer 21

Affected Dentin

Question 22

Affected Dentin is also known as _______.

Answer 22

Carious Inner Dentin

Question 23

Zone of bacterial invasion marked by widening and distortion of the dentinal tubules, which are filled with bacteria, cannot remineralize, turbid dentin.

Answer 23

Infected Dentin

Question 24

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.

Answer 24

Infected Dentin

Question 25

Infected Dentin is also known as __________.

Answer 25

Outer carious dentin

Question 26

Caries that are usually seen where there is a gingival recession and the oral hygiene is poor.

Answer 26

Cementum Caries

Question 27

Clinically, the cementum lesion appears as ___________ and ___________ in cross sections and progresses rapidly because of the lack of enamel covering.

Answer 27

saucer-shaped cavities and U-shaped

Question 28

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.

Answer 28

Actinomyces

Question 29

Two Types of Cementum Caries

Answer 29

1. Active Root Caries
2. Arrested Root Caries

Question 30

This specific response to the root caries is either partially or completely occluding the tubules partially or completely occluding the tubules with mineral crystals.

Answer 30

Sclerotic response

Question 31

The carious lesion starts on the lateral walls of the fissures that eventually flare laterally at the bottom of the pit.

Answer 31

Pits and Fissure Caries

Question 32

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.

Answer 32

enamel rod

Question 33

Bacteria found in the pits and fissures of newly erupted teeth.

Answer 33

Gram positive cocci,
Streptococcus sanguis

Question 34

Bacteria found in carious pits and fissures.

Answer 34

Streptococcus mutans

Question 35

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.

Answer 35

cariogenic biofilm attachment

Question 36

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.

Answer 36

Smooth Surface Caries

Question 37

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 _____.

Answer 37

Base - DEJ
Apex - Points outward in the enamel

Question 38

Smooth surface caries on enamel is also a triangle or V -shaped, where the base is on the _____ and the apex is at the _____.

Answer 38

Base - enamel
Apex - DEJ

Question 39

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.

Answer 39

Base - DEJ
Apex - Pulp

Question 40

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.

Answer 40

apex-to-base