Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS2 Oral Biology - Histology > (2) Anatomy and Histology of the Periodotium - Enamel (B) > Flashcards

(2) Anatomy and Histology of the Periodotium - Enamel (B) Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What section has to be taken to view enamel?

A

ground section

completely lost in demineralised section

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Can immature enamel be studied by a demineralised section?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the basic structural units of enamel?

A

Prisms (rods) / enamel prisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What comprises each enamel prism?

A

several million hydroxyapatite crystals packed into a long thin rod 5-6um in diameter and up to 2.5mm in length.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What separates each prism?

A

inter-rod substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do you differentiate enamel prisms and inter-rod substances?

A

Crystals with different orientation (deviate by 40-60°)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name structures A and B

A

A = interrod
B = rod

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do you identify a prism boundary?

A

a sudden change in crystallite orientation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How would you describe a prism in a cross-section?

A

keyhole pattern (pattern III)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where does the tail of a prism lie? (cross section)

A

The tail of one prism lies between the heads of the two adjacent prisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is responsible for the optical appearance at a prism boundary?

A

An abrupt change of crystal orientation at the prism boundary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Name feature D

A

head of prism shown by cross-section

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Do the crystal heads run parallel with one another?

A

Yes

along the long axis of the prism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What cut are each of these images?

A

cross sections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Does the keyhole pattern give strength to enamel?

A

YES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How to we see the difference between the head and tale sections?

A

the different orientation of crystals

In the tail, the crystals diverge gradually to become angled at 65-70° to the long axis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How would you describe the prism head and tail crystal orientations?

A

The change from head to tail is gradual in each prism, however a tail of one prism shows a sudden divergence from the head of an adjacent prism.

the crystal orientation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What cut of the enamel can you see the boundaries of prisms easily?

A

the longitudinal

the run parallel running back

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens every 10-13 layers of prism?

A

Every 10-13 layers of prisms follow the same direction, but blocks above and below follow paths in different directions.

= Hunter-Schreger bands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is shown here

A

Hunter- Schreger bands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the banding pattern of enamel called?

A

Hunter- Schreger bands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the approx. width of Hunter- Schreger bands?

A

50um

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Are Hunter- Schreger bands visible?

A

visible due to light reflection in different directions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why cant you usually see visible due to light reflection in different directions in enamel?

A

In the outer ¼ of enamel, all prisms run in the same direction and so there is no banding.

25
Q

How do prisms appear over the cusps of enamel?

A

appear twisted around each other in a complex arrangement known as gnarled enamel

26
Q

What is shown here?

A

Prisms over the cusps appear twisted around each other in a complex arrangement known as gnarled enamel

27
Q

How tick is the outer surface layer of enamel in primary teeth?

A

20-100um

28
Q

How thick is the outer surface layer of secondary enamel?

A

20-70um

29
Q

What is the outer layer of enamel called?

A

aprismatic.

30
Q

How are the crystallites arranged in aprismatic enamel?

A

The crystallites are aligned at right angles to the surface and parallel to each other.

31
Q

Is the apirsmatic layer of enamel more or less mineralised to inner layers?

A

highly mineralised

32
Q

Why is the outer layer of enamel more highly mineralised?

A

The surface layer is more highly mineralised than the rest of the enamel. This is attributed to the absence of prism boundaries where organic material is located.

33
Q

How would you describe the way enamel is formed?

A

Incrementally

34
Q

Describe how enamel is formed incrementally

A

Enamel is formed in increments: periods of activity alternating with periods of inactivity.

This results in incremental lines: short period (cross striations) and long period (enamel striae).

35
Q

How do cross striations appear on enamel?

A

Cross striations appear as lines crossing the enamel prisms at right angles to their long axes.

They reflect a diurnal rhythm (daily increments of growth).

36
Q

When do cross striations appear closer together?

A

Closer to each other near the enamel-dentine junction.

37
Q

What is shown in the histological diagram?

A

stria of retzius

(enamel striae)

Enamel striae run obliquely across the prisms. They represent incremental lines and are known as the striae of Retzius.

38
Q

Do striae of retzius reach the surface of the enamel?

A

no

39
Q

How to stria of retzius appear in cross section of a tooth?

A

run circumferentially like the rings of a tree.

40
Q

How many cross striation are there between enamel and adjacent stira?

A

7-10

This suggests weekly intervals.

41
Q

When do the stria of retzius (cross section) run closest together?

A

cervically

42
Q

How to enamel stria appear on the surface of teeth?

A

appear as fine grooves running circumferentially around the crown.

43
Q

What are the stria on the surface of teeth referred to as?

A

The lines are termed Perikymata grooves, with perikymata ridges in between.

44
Q

Name the feature

A

Perikymata grooves

45
Q

How does surface enamel compare to subsurface enamel?

A

Physically and chemically, surface enamel differs from subsurface enamel.

Surface enamel is harder, less porous, less soluble and more radio-opaque.

Richer in trace elements.

Less carbonate.

Aprismatic, therefore highly mineralised.

46
Q

What are the arrows pointing to?

A

The pits are within the perikymata.

formed on protected areas of enamel

47
Q

What do the small pits on perikymata represent?

A

They mark the ends of ameloblasts (prism end markings.
1-1.5μm in depth.

48
Q

What is the neonatal line?

A

prominent enamel stria

49
Q

What are the arrows pointing to?

A

enamel caps

50
Q

What is an enamel cap?

A

Enamel caps are small elevations 10-15μm across.

51
Q

How does an enamel cap form?

A

they result from enamel deposition on top of debris late during tooth development.

52
Q

What are the arrow pointing to?

A

focal holes

53
Q

What are focal holes on the surface of enamel?

A

Focal holes are depressions on the surface.

loss of mineralised material on top of organic material

54
Q

How do focal holes form?

A

Loss of enamel caps with the underlying material.

this happens through abrasion or attrition.

55
Q

What is shown here? (surface enamel)

A

Enamel brochs are elevations on the enamel surface.

56
Q

Where is the enamel broch usually found?

A

the cemento-enamel junction

57
Q

What tooth do you usually see the enamel broch?

A

premolar 6s

58
Q

What does an enamel broch look like?

A

extra piece of enamel with radiating crystalites

59
Q

What type of microscopy is used here?

A

transmission

BDS2 Oral Biology - Histology (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions