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DENT 1020 > Dental Unit - Enamel > Flashcards

Dental Unit - Enamel Flashcards

1
Q

Where is root sheath located? What is it filled with?

A

Between rods and inter rods

contain organic material

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2
Q

Why is enamel brittle?

A

It doesn’t contain collagen (protein – organic)

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3
Q

What is lamellae?

A

Appears as a crack from the enamel surface

Filled with organic material

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4
Q

Where is tuft? Why is it present?

A

from dentinoenamel junction towards outer surface

Caused by changing in orientation of rods

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5
Q

Where is spindle? Why is it present?

A

From dentinoenamel junction towards outer surface

Trapped odontoblastic process in ameloblasts during mineralization

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6
Q

Where is gnarled enamel? How does it look?

A

At cusp tip

Appears as twisted rods

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7
Q

Where are hunter-schreger bands? Why are they present?

A

inner two-thirds of enamel (dark & light lines)

optical illusions - change in direction of enamel rods

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8
Q

Why are Straie of Retzius present?
Name of the significant one?
What would be formed if it extends onto outer surface of enamel?

A

deposition of enamel over time (incremental growth)
Neo-natal line
Perikymata on outer surface

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9
Q

5 Main Changes of Enamel over time

A
  1. Less permeable
  2. Darken
  3. More sensitive
  4. Reduced risk for dental caries
  5. Harder - more mineralized
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10
Q

5 Types of Dentine (According to position)

A
  1. Mantle Dentine
  2. Primary Dentine / Circumpulpal Dentine
  3. Secondary Dentine
  4. Tertiary Dentine
  5. Predentin
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11
Q

2 Types of Tertiary Dentine

A
  1. Reactionary Dentine - by existing odontoblasts

2. Reparative Dentine - by newly formed odontoblasts

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12
Q

A characteristic of predentin

A

unmineralized - principally consists of collagen

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13
Q

When would secondary dentine be developed?

A

After completion of root formation

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14
Q

How is secondary dentine different from primary dentine? (Give 2 differences) What function does this serve?

A

Less regular tubular structure

Tubules in secondary dentine sclerose more readily -> reduce permeability -> protect pulp

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15
Q

What are dead tracts sealed off by? What function does this serve?

A

Reparative dentine

Protect pulp from infection

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16
Q

5 types of dentine histologically

A
  1. Dentinal tubules
  2. Peritubular dentine - highly calcified
  3. Interglobular dentine - unmineralized/hypomineralized (in primary dentine)
  4. Intertubular dentine
  5. Sclerotic dentine
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17
Q

Cells forming tertiary dentine and eventually being included inside.

A

Osteodentine

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18
Q

Orientation of incremental growth lines

Where are they found?

A

Right angle to dentinal tubules

In dentine

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19
Q

What is contour lines of Owen caused by? Name of the wide line?

A

accentuated efficiencies in mineralization

Neo-natal Line

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20
Q

Where is granular layer of Tomes found?

What is it resulted from?

A

In root dentine
Near cementum
Resulted from the special arrangement of collagen & noncollagenous matrix proteins

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21
Q

4 Zones in pulp

A
  1. Odontoblastic Zone
  2. Cell-free zone of Weil
  3. Cell-rich zone
  4. Pulp core
22
Q

Where do blood vessels enter & exit the pulp?

A

Through apical & accessory foramina

23
Q

Name of extensive plexus of nerve in pulp.

In which part of pulp is it located?

A

Subodontoblastic plexus of Raschkow

in cell-free zone of Weil

24
Q

Another name of pulp stone. What is it?

A

Denticle

Discrete calcified mass

25
Q

How is true pulp stone different from other pulp stones?

A

It is surrounded by cells resembling odontoblasts

may contain tubules

26
Q

5 Characteristics of Dentine

A
  1. Avascular
  2. Yellowish
  3. Permeable
  4. Hard tissue
  5. Elastic
27
Q

4 Functions of Pulp

A
  1. Formative: produces dentine that surrounds it
  2. Nutritive: nourishes avascular dentine
  3. Protective: carries nerves that give sensitivity
  4. Reparative: capable of producing new dentine as required
28
Q

Which 2 structures meet at apical foramen?

A

Pulp & periodontal ligament

29
Q

4 Changes of pulp with age

A
  1. flattened fibroblasts
  2. smaller & eccentric apical foramen when compared to developing tooth
  3. Less undifferentiated mesenchymal cells -> diminished regenerative potential
  4. Increase in overall collagen content
30
Q

Specialized fibrous joint formed by periodontium

A

gomphosis

31
Q

2 Types of cementum and their role

A
  1. Cellular cementum - associated with repair of periodontal tissues, adaptive role in response to tooth wear & movement
  2. Acellular cementum - provides attachment for tooth
32
Q

Where is cellular cementum confined to? In what kind of tooth is it often absent in?

A

confined to apical third & inter radicular region

often absent in single-rooted teeth

33
Q

3 Types of cementoenamel junction

A
  1. Cementum overlaps with enamel (60%)
  2. Meet at butt joint (30%)
  3. Gap in between, exposing dentine (10%)
34
Q

3 Characteristics of cementum

A
  1. Avascular
  2. Hard - mineralized
  3. Cellular/ Acellular
35
Q

Origin of periodontium (except gingiva)

A

Ectomesenchymal

36
Q

3 Parts of alveolar process

A
  1. Cortical plate
  2. Central spongiosa
  3. Bone lining the alveolus
37
Q

What is alveolar bone referred to radiographically? (2 Names) Which part of the bone is it referring to?

A

Lamina dura / Bundle bone

Compact bone

38
Q

Where is trabecular bone absent?

A

Anterior teeth

39
Q

4 functions of periodontal ligament

A
  1. Support teeth in sockets
  2. Permit teeth to withstand forces of mastication
  3. Attach teeth to bone
  4. Sensory function - for proper positioning of jaws
40
Q

2 Types of cells in cellular cementum

A
  1. Cementoblasts

2. Cementocytes

41
Q

7 Types of cells in periodontal ligament

A
  1. Fibroblasts
  2. Osteoblasts
  3. Osteoclasts
  4. Epithelial cell rests of Mallasez
  5. Macrophages
  6. Undifferentiated mesenchymal cells
  7. Cementoblasts
42
Q

5 Principal fibre bundles in periodontal ligament

A
  1. Alveolar crest group
  2. Horizontal group
  3. Oblique group
  4. Apical group
  5. Inter radicular group
43
Q

Embedded portion of principal fibre bundles in cementum & bone

A

Sharpey’s fibre

44
Q

Where is gingival ligament found?

A

In lamina propria

45
Q

5 fibre bundles in gingival ligament

A
  1. Dentogingival group
  2. Alveologingival group
  3. Circular group
  4. Dentoperiosteal group
  5. Transseptal fibre system
46
Q

Type of elastic fibre in periodontal ligament ad its function

A

Oxytalan

Regulate vascular flow

47
Q

What is sulcus lined by?

A

oral sulcular epithelium (non-keratinized)

48
Q

What type of epithelium is junctional epithelium? What is it derived from? What is its function?

A

Stratified squamous epithelium
non-keratinized
Derived from reduced enamel epithelium
Provides attachment of gingiva to tooth through epithelial attachment

49
Q

Where are the 2 ends of periodontal ligament fibre bundles embedded into?

A

Bone

Cementum

50
Q

3 Changes of dentine with age

A
  1. Continuously laid secondary dentine
  2. More sclerotic dentine (occluded with calcified material) -> glassy appearance
  3. Obliteration of dentinal tubules by peritubular dentine
51
Q

4 Types of non-carious tooth loss

A
  1. Attrition
  2. Abrasion
  3. Erosion
  4. Abfraction

DENT 1020 (7 decks)

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