A

Question 1

Arrested caries in Dentin:

Answer 1

Usually in large cavities in occlusal surfaces lack food retention and receive the washing effect of saliva  eburnated dentine.
N.B
dentine=hard brown polished surface of dentine that does not catch the probe.
eburnated

Question 2

Arrested caries in Dentin:

Answer 2

Usually in large cavities in occlusal surfaces lack food retention and receive the washing effect of saliva  eburnated dentine.
N.B
dentine=hard brown polished surface of dentine that does not catch the probe.
eburnated

Question 3

According to onset

Answer 3

a-1ry caries

b-Recurrent of 2ry caries: under defective restoration

c-Residual caries: Which is not removed during a restorative procedure

Question 4

Zones of early dentine caries:

Answer 4

1)Zone of fatty degeneration of tomes fibers (odontoblastic processes):

due to irritation by acid→ Dead tracts.

Dead tracts: are the empty dentinal tubules

resulting from degeneration of the odontoblasts and their processes by bacterial acid irritation which appear opaque in ground sections examined by transmitted light.

The end of the dead tracts are occluded by

sclerotic dentine.

2) Zone of dentinal sclerosis:

Translucent areas.

zone beneath carious

3) Zone of demineralization:

Decalcification of dentinal tubules

allow the packing of bacteria inside.

Question 5

Zones of early dentine caries:

Answer 5

1)Zone of fatty degeneration of tomes fibers (odontoblastic processes):

due to irritation by acid→ Dead tracts.

Dead tracts: are the empty dentinal tubules

resulting from degeneration of the odontoblasts and their processes by bacterial acid irritation which appear opaque in ground sections examined by transmitted light.

The end of the dead tracts are occluded by

sclerotic dentine.

2) Zone of dentinal sclerosis:

Translucent areas.

zone beneath carious

3) Zone of demineralization:

Decalcification of dentinal tubules

allow the packing of bacteria inside.
4. 4) Zone of bacterial invasion:

Pioneer bacteria: is the 1st generation of bacteria that

invades the dentinal tubules. Each dentinal tubule is invaded by single isolated type of bacteria.

Acidogeneic bacteria is found first then proteolytic bacteria predominate in deep caries.

In this zone softening of D.tubule occurs with the intense packing of bacteria & the bending and compression of adjacent tubules occur to form beaded dentinal tubule.

Question 6

Late dentine caries started with the formation of two structures:

Answer 6

1
) Liquefaction foci: are ovoid foci filled with necrotic debris that result from the local coalescence and breakdown of dentinal tubules.
They are parallel to the course of D.tubule.
2
) Transverse clefts: they are formed at right angles to the D.tubules due to the extension of caries along the lateral branches.