(7) Histopathology Of Dental Caries - Enamel

Question 1

What type of caries develop slowly?

Answer 1

Slowly/Chronic caries

Most common

Question 2

What type of section do we look at to study caries?

Answer 2

Ground

Question 3

What are the stria of Retzius?

Answer 3

incremental growth lines or bands seen in tooth enamel

During crown formation

Question 4

What do early lesions appear as?

Answer 4

Cone shaped

Question 5

What does the apex of the carie cone point towards?

Answer 5

The amelodentinal junction

Question 6

Name A-D in the army lesion

Answer 6

A = Stria of Retzius
B = surface enamel
C = apex of cone
D = amelodentinal junction

Question 7

What does colour represent in a ground section?

Answer 7

Different degrees of mineralisation

White = highly mineralised

Question 8

Where does the base of the carie attach to?

Answer 8

Enamel surface

Question 9

Name the zones of the early lesion

Answer 9

A = surface layer
B = body of lesion
C = dark zone (active progress)
D = translucent zone

Question 10

What is the deepest zone of a early dental caries?

Answer 10

Translucent zone

Question 11

What is the advancing edge of the lesion?

Answer 11

Translucent zone

Question 12

Is the advanced lesion more porous than enamel?

Answer 12

Yes

Question 13

When can you not see the translucent zone?

Answer 13

Of the lesion is advancing rapidly

Question 14

What has a higher volume of pours, dark zone or translucent zone?

Answer 14

Dark zone (2-4%)

Question 15

Why does the dark zone have a variation in pose size?

Answer 15

Demineralisation due to acidic attack and remineralisation due to the precipitation of the demineralised part of the translucent zone.

Question 16

When is the dark zone narrow?

Answer 16

If the lesion is advancing rapidly

Question 17

Why is the dark zone wider when the Edison progresses slowly?

Answer 17

More time for remineralisation and demineralisation to take place

Question 18

What section of the lesion has the highest pore volume?

Answer 18

The body of the lesion

(5-25%)

Question 19

What is different about the hydroxyapatite crystals in the body of the lesion compared to enamel?

Answer 19

More pours, they’re will be water and organic material that replace the lost minerals

Question 20

What section has very prominent Stria of Retzius?

Answer 20

The body of the lesion

Question 21

How does the surface zone of the lesion compare to normal enamel with regards to their mineralisation?

Answer 21

The surface zone is hypermineralised

Because of mineral precipitation from the oral cavity and demineralised deeper layers

Question 22

What are the 6 stages of enamel histopathogenesis?

Answer 22

1. Subsurface translucent zone.
2. Enlarges and a dark zone develops in the centre.
3. Body of the lesion forms in the centre of the dark zone. (White spot).
4. If stained, brown spot
5. When reaching the dentinoenamel junction, caries spread laterally undermining adjacent enamel (bluish white)
6. After a critical stage, enamel breaks forming a cavity (could take place before step 5).

Question 23

What is the critical point of an enamel carie formation?

Answer 23

When the dentin can no longer support enamel and the enamel breaks

Question 24

What zone of the enamel carie is most highly mineralised?

Answer 24

The surface zone

Question 25

What enamel carie is shown here?

Answer 25

Fissure caries

Question 26

How do fissure caries form?

Answer 26

Caries spread outwards to adjacent enamel and downwards towards dentin

Lesions meet at the base of fissures

Question 27

Where do caries start forming on the fissure caries?

Answer 27

The walls of the fissures

Question 28

Where does the base of the fissure caries face?

Answer 28

Faces the dentinoenamel junction

Question 29

What type of carie is shown here?

Answer 29

Pit or fissure lesion

Question 30

Why are enamel and dentin caries different?

Answer 30

Enamel almost fully mineralised

Dentin has big percentage of organic component - living tissue. A reaction from this tissue