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Flashcards in Chapter 21 Deck (45)
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1

When does root formation begin?

Begins after the outline of the crown has been established but before the full crown is calcified

2

Layers of OEE and IEE make up what?

Epithelial root sheath (Hertwig's epithelial root sheath)

3

Epithelial root sheath (Hertwig's epithelial root sheath)

Begin to undergo rapid miotic division and grow deep into the underlying connectice tissues - The beginning of root formation

4

Dentinocemental junction

Some epithelial root sheath cells do not pull away and may become ameloblasts, forming small globes of enamel on the surface of the dentin

5

Enamel pearls

Found in bifurcations and trifurcations of roots

6

A hard, yellowish substance covering the root of the tooth

Cementum

7

% of inorganic hydroxypatite crystals in cementum

45% to 50%

8

% of organic components of water in cementum

50% to 55%

9

CEJ

First seen at the cervical line of the tooth, also called the cementoenamel

10

How many different relationships with the enamel of the crown

3

11

60% of the cases of cementum

overlaps the enamel

12

30% the cementum meets

the enamel at a sharp junctions

13

10% of the cases the cementum

and enamel do not meet, leaving dentin exposed at the cervical line

14

Acellular cementum

All of the cementoblasts remain on the surface rather than becoming trapped within the cementum

15

Where is acellular

In the cervical two thirds of the root

16

Cellular cementum

More vital than acellular cementum and therefore more responsive to remodeling itself

17

Where is cellular cementum

Apical 1/3 of the root

18

The cellular at the apex of the root tends to

inrease in thickness with the passage of time and as a result of stress causing thickening (hypercementosis)

19

Makes extraction a bit more difficult than usual

Hypercementosis

20

Periodontal membrane (ligament)

Forms the middle of the layer of cells in the old dental sac, the ends of the periodontal fibers become surrounded by cementoblasts, whose secretion hardens around the ends of the fibers, attaching them to the cementum

21

Parts of the periodontal ligament embedded in cementum are known as

Sharpey's fibers

22

Sharpey's fibers (SF)

Parts of the PDL surrounded by cementum on the tooth side and alveolar bone on the opposite side in the wall of the tooth socket

23

Alveolar bone

Is the bone of the upper or lower jaw that makes up the sockets for the teeth

24

3 layers of alveolar bone

Cortical plate
Cribiform plate or alveolar bone proper
Spongy or cancellous bone

25

First layer of alveolar bone

Layer of compact bone on the buccal or lingual surface is referred to as the cortical plate of bone.

26

Second layer of alveolar bone

Called the cribriform plate or alveolar bone proper. Radiographically it is referred to as the lamina dura

27

Bundle bone

The tooth socket is constantly being remodeled and additional bone laid down on the cribriform plate

28

A thickened lamina dura is caused by

bundle bone being laid down on the cribriform plate and is an indication of occlusal trauma to that tooth or teeth

29

Between the coritcal plate and cribriform plate

Layer of spongy or cancellous bone (3rd layer)

30

Spongy bone is a

bone marrow

31

Interproximal alveolar crest

The spongy bone and the crest of bone that joins two sockets

32

Three groups of the periodontal ligament

Gingival fibers, transseptal fibers, and alveolodental fibers

33

After a person has had a root canal on a tooth, it is still possible to feel pain at times from the

periodontal ligament

34

Gingival fibers

Run from the cementum into the free and attached gingival area; support the gingiva

35

Circular gingival fibers

run around the tooth in free gingiva and hold gingiva against the tooth

36

Transseptal fibers

Run from the cementum of the interproximal portion of one tooth, across the alveolar crest of bone, to the cementum of the interproximal portion of the adjacent tooth; hold the teeth in interproximal contact

37

Alveolodental fibers

Run from cementum to alveolar bone

38

what are the alveolodental fiber groups

Alveolar crest group
Horizontal group
Oblique group
Apical group
Interradicular group

39

Alveolar crest group

Runs from cementum, slightly apical to the alveolar crest of bone; helps resist horizontal movements of teeth

40

Horizontal group

Runs from cementum horizontally to the alveolar crest; helps resist horizontal movement

41

Oblique group

runs from cementum cornily into the alveolar bone; main fiber group for resisting occlusal stresses

42

Apical group

Runs from apex of the tooth into the adjacent alveolar bone; resists forces trying to pull the tooth from its socket

43

Interradicular group

Found only on multirooted teeth; runs from the alveolar crest of the bone between the roots of the tooth to adjacent cementum; resists the forces trying to remove the tooth

44

What happens when a tooth is lost

The posterior to the missing tooth will tilt forward into the unoccupied space (mesial drift)

45

If a tooth if moved too fast in orthodontic treatment

It is possible that the fibers attaching the tooth to bone will be torn out of their attachment; Before they can be re-embedded, the tooth could conceivably loosen and be lost or could cause external root resorption