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Flashcards in Periodontium Deck (61)
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1

What structures make up the periodontium?

Cementum
PDL
Bony socket
Gingiva facing the tooth

2

What are the two types of gingiva that face the tooth?

Junctional epithelium
Sulcular epithelium

3

What is the only perio structure not attached to the tooth

Sulcular epithelium

4

What immediately precedes periodontal development?

Root dentinogenesis

5

What is the coordination of periodontal development?

Cementoblasts and osteoblasts secrete their organic matrix
Then PDL fibroblasts secrete their organic matrix
Then the bone and cementum mineralize

6

How does the PDL develop during tooth eruption?

Collagen fiber bundles are added apically
The orientation of collagen fiber bundles change - they start obliquely, then horizontal, and then coronally oblique

7

How does the PDL develop after tooth eruption?

The thickness of collagen fiber bundles increase

8

What are the two types of cementum?

Primary Cementum
Secondary Cementum

9

Primary Cementum

Forms as the tooth is erupting
Mainly acellular
covers the coronal 2/3 of the tooth
Most important in attachment
More mineralized

10

Secondary Cementum

Formed after at least half the root is formed, around the time the tooth emerges in the oral cavity
Mainly cellular
Apical 2/3 of the root
Less mineralized
More important in adaptation

11

T/F - Primary and Secondary Cementum overlap in the middle 1/3 of the root

True - The Secondary cementum overlies the Primary

12

Why is cementum and dentin so firmly attached?

It is a consequence of the collagen fibers of the tissues intermingling between mineralization

13

As primary cementum is laid down, what happens to the cementoblasts?

They retreat towards the future PDL
They don't become entrapped in the cementum, but persist in the adult PDL

14

Epithelial Rests of Mallasez

Fragments of HERS that remain in the PDL

15

What is the main difference between primary and secondary cementogenesis?

In secondary cementogenesis, the cemntoblasts become trapped in cementum matrix - they're then called cementocytes

16

What does the sulcular epithelium derive from?

Embryonic oral epithelium

17

What does the junctional epithelium derive from?

Reduced enamel epithelium

18

Do cementoblasts derive from the dental follicle or the HERS?

We don't know - maybe both?

19

What is at the mineralization front of periodontal development?

Sialoprotein

20

Cementum

Hard connective tissue that covers the dentin of the root - similar to bone

21

How much of cementum is organic

45-55%
(90% collagen - mostly type I)

22

How much of cementum is inorganic?

50-55%

23

T/F - Cementum is secreted through life and not normally resorbed

True - Can triple in size from age 16-70

24

What are the functions of cementum

Attach tooth to the jaw
Protect the root dentin
Adapt to masticatory forces

25

How thick is the cementum in the CEJ v the apex of the root.

CEJ = thin (20-50um)
Apex = thicker (150-200um)

26

What are the types of joints at the CEJ?

Cementum overlaps enamel (60%)
Cementum buts up agains enamel (30%)
Gap between the cementum and enamel (10%)

27

Acellular extrinsic fiber cementum

Importance in attachment
Collagen fibers are at right angles to cementum surface
Has Sharpey's Fibers

28

Sharpey's Fibers

Fibers of the PDL that extend into the mineralized area

29

Cellular intrinsic cementum

Important in adaptation
Collagen fibers are parallel to the surface of cementum
Called intrinsic fibers because fibroblasts get caught in the cementum and are called cementocytes

30

Mixed fiber cementum

Some intrinsic, and some extrinsic
Make up most of the secondary cementum - made in the second wave of secondary cementum and found closer to the root apex