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Oral Histology > Periodontium > Flashcards

Periodontium Flashcards

(61 cards)

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1
Q

What structures make up the periodontium?

A

Cementum
PDL
Bony socket
Gingiva facing the tooth

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2
Q

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

A

Junctional epithelium

Sulcular epithelium

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3
Q

What is the only perio structure not attached to the tooth

A

Sulcular epithelium

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4
Q

What immediately precedes periodontal development?

A

Root dentinogenesis

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5
Q

What is the coordination of periodontal development?

A

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

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6
Q

How does the PDL develop during tooth eruption?

A

Collagen fiber bundles are added apically

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

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7
Q

How does the PDL develop after tooth eruption?

A

The thickness of collagen fiber bundles increase

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8
Q

What are the two types of cementum?

A

Primary Cementum

Secondary Cementum

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9
Q

Primary Cementum

A 
Forms as the tooth is erupting
Mainly acellular
covers the coronal 2/3 of the tooth
Most important in attachment
More mineralized
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10
Q

Secondary Cementum

A 
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
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11
Q

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

A

True - The Secondary cementum overlies the Primary

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12
Q

Why is cementum and dentin so firmly attached?

A

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

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13
Q

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

A

They retreat towards the future PDL

They don’t become entrapped in the cementum, but persist in the adult PDL

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14
Q

Epithelial Rests of Mallasez

A

Fragments of HERS that remain in the PDL

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15
Q

What is the main difference between primary and secondary cementogenesis?

A

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

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16
Q

What does the sulcular epithelium derive from?

A

Embryonic oral epithelium

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17
Q

What does the junctional epithelium derive from?

A

Reduced enamel epithelium

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18
Q

Do cementoblasts derive from the dental follicle or the HERS?

A

We don’t know - maybe both?

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19
Q

What is at the mineralization front of periodontal development?

A

Sialoprotein

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20
Q

Cementum

A

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

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21
Q

How much of cementum is organic

A

45-55%

90% collagen - mostly type I

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22
Q

How much of cementum is inorganic?

A

50-55%

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23
Q

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

A

True - Can triple in size from age 16-70

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24
Q

What are the functions of cementum

A

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

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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
31
Cementocytes
Cementobalsts that got caught in the organic matrix | No longer make cementum - may be inactive
32
Periodontal ligament
Soft connective tissue between the cementum and the bony wall of the socket Made up of large collagen fiber bundles with ends embedded in cementum/bone Continuous with the gingival connective tissue cervically and apical foramen apically
33
How thick is the periodontal ligament?
.15-.40 mm (thin) | gets thinner with age
34
What cells are most numerous in the PDL?
Fibrobalsts
35
What do fibroblasts do in the PDL?
Secrete and degrade collagen Cell-Cell junctions Cell-ECM junctions
36
What non-fibroblasts cells are found in the PDL?
``` Cementoblasts Osteoblasts/clasts Epithelial rest of Mallasez Immune cells Stem cells ```
37
What is the collagen turnover in Gingiva v PDL?
``` Gingiva = 5 weeks PDL = 1 week ```
38
What is the cell volume of Gingiva v. PDL?
``` Gingiva = 8% PDL = 40% ```
39
What is the proliferation rates of Gingiva v. PDL?
``` Gingiva = lower PDL = higher ```
40
What is the importance of Cell-ECM junctions
Functional link between occlusal forces and fibroblasts Translate forces applied to fibroblast into physiological responses Maintain orientation of fibroblasts in PDL
41
What is the structure of Cell-ECM junctions?
There are a variety of different junctions | They all interact with collagen in the ECM either by a single transmembrane molecule or several
42
Where are cementobalsts in the PDL?
Near cemetnum
43
Where are the osteoblsats and osteoclasts located in the PDL?
At the interface of the PDL and alveolar bone
44
Undifferentiated Mesenchymal Cell characeristics in the PDL
Perivascular location | Pluripotent
45
What types of fibers are in the ECM of the PDL?
Types I and III Collagen | Oxytalin
46
What is in the ground substance of ECM of PDL?
PGs and the associate GAGs | Glycoproteins
47
Cementicle
Spherical calcified mass in the PDL | Similar to pulp stones in the pulp
48
What are the principal fiber groups of the PDL?
``` Alveolar crest Horizontal fibers Oblique fibers Apical fibers Interradicular septum ```
49
Alevolar crest fibers
Attach cementum to the crest
50
Horizontal fibers
Attach cementum to the alveolar bone just below the crest
51
Oblique fibers
Attach cemntum to the alveolar bone in an oblique orientation that suspends the tooth in the socket
52
Apical fibers
Attach the apex of the tooth in the alveolar bone
53
Interradicular septum
Only found in teeth with multiple roots | Extend between the cementum and interredicular septum of alveolar bone
54
Gingival ligament
Important for maintaining the PDL and supporting the toth
55
Transseptal ligament
From cementum of tooth, arching over the alveolar bone, and attaching to the cementum of the adjacent tooth
56
T/F - The tooth is heavily vascularized
True
57
What are the 2 routes taken by blood vessels to supply the PDL?
1) Enter the alveolar bone and then pierce the foramina in the wall of the bony socket - via perforating arteries 2) Branch near the apical foramen and directly enter the PDL
58
What fibers signal pain in the PDL?
Small fibers - A-delta - C
59
What fibers signal proprioception in the PDL?
Large fibers | -A-beta
60
What are features of A-beta PDL fibers
``` Intermingle with collagen fibers Highly sensitive Code for the amount of force Code for the direction of force Send info to CNS regarding chewing Underlie out ability to localize stimuli applied to teeth ```
61
Alveolar processes
Bone of jaw that contains sockets for teeth | Spongy bone

Oral Histology (12 decks)

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