Periodontium

Question 1

What are the three principle components of the periodontium?

Answer 1

1-Alveolar process
2-Cementum
3-Periodontal Ligament

Question 2

A fibrous peg-in-socket joint is called what?

Answer 2

Gomphosis

Question 3

What is the origin of osteoblasts?

Answer 3

Surrounding mesenchymal tissue

Question 4

What is the origin of cementoblasts?

Answer 4

Ectomesenchymal cells driven by HERs/follicle cells

Question 5

What is the origin of PDL fibroblasts?

Answer 5

Ectomesenchymal/follicle cells

Question 6

Periodontium contains ___ out of ____ types of mineralized tissue found in the oral cavity

Answer 6

3 out of 4

Question 7

How is alveolar process formed?

Answer 7

Intramembranous ossification (Mesenchyme direct to bone, no cartilage intermediate)

*Begins during 8th week of uterine life

Question 8

What is the main influence driving the development of the alveolar process?

Answer 8

dental follicle

Question 9

Compact bone (cribriform plate, lamina dura) lines the “tooth socket” and is called?

Answer 9

Alveolar bone proper

Question 10

What are the compact and trabecular bone components of the supporting alveolar bone?

Answer 10

• Compact: Cortical plates

- Trabecular: Central spongiosa

Question 11

What are the 3 descriptions for alveolar bone proper?

Answer 11

1-Cribriform plate (anatomical term)
2-Lamina Dura (radiographic term)
3-Bundle bone (histological term)

Question 12

Which side of alveolar bone proper has a higher remodeling rate due to constant adaptation to tooth movements and is thus primarily woven bone?

Answer 12

Inner (towards PDL)

*outer is more lamellar bone, continuous with supporting alveolar bone

Question 13

The junction of the cortical plate and alveolar bone proper is referred to as?

Answer 13

Alveolar crest

*thinner in maxilla, thickest in premolar and molar region of mandible

Question 14

What are the two main components of the central spongiosa?

Answer 14

1-Trabecular bone supporting alveolar bone proper and cortical plate
2-Marrow (red in young, yellow in aged)

Question 15

Bony region between roots of a single tooth are called?

Answer 15

Interradicular septum

Question 16

Bony region between adjacent teeth are called?

Answer 16

Interalveolar septum

Question 17

What are 4 functions of alveolar bone?

Answer 17

1-Protection and structure of the socket
2-Attachement of Sharpeys fibers of the PDL
3-Support of tooth roots, especially facial/lingual
4-Distribution of loading from the tooth and PDL to the surrounding bone

Question 18

What differentiates into fibroblasts to produce and organize collagen fibers in an oblique orientation to form the PDL?

Answer 18

Ectomesenchyme cells from the dental follicle

Question 19

What 3 types of collagen are present in the PDL?

Answer 19

Type I, III, XII

*typically ranges in width between .15 mm to .38 mm

Question 20

What is the main elastic fiber of the PDL?

Answer 20

Oxytalan (not elastin)

*Typically associated with vasculature

Question 21

Where are arteries found in the PDL?

Answer 21

loose connective tissue “bays” called interstitial areas tucked into the principal fiber bundles

Question 22

Sensing nociception and pressure, what are the 4 types of nerve endings?

Answer 22

1-Free nerve endings (most prevalent, nociceptive/mechanoreceptive, reaches cementum)
2-Ruffini’s Corpuscles (bulbous dendritic endings, slow mechanoreceptive associated with collagen)
3-Coiled nerve endings around mid-region (unknown function)
4-Spindle nerve endings surrounding fibrous capsule (unknown function)

Question 23

What are the 5 PDL fibers in cervical-apical order?

Answer 23

1-Alveolar crest group (CEJ to alveolar socket rim)
2-Horizontal group (cementum to alveolar socket)
3-Oblique group (most numerous, oblique angle from cementum most of the way down root)
4-Apical group (root apex to underlying bone)
5-Interradicular group (multi-rooted teeth, attach to interradicular septum)

Question 24

What are the 5 groups of Gingival ligaments?

Answer 24

1-Dentogingival group (most numerous, cervical cementum to lamina propria of free and attached gingiva)
2-Alveologingival group (alveolar crest to lamina propria)
3-Circular group (around the neck of the tooth)
4-Dentoperiosteal group (apically from cementum to periosteum of outer cortical plate)
5-Transseptal fibers (cementum over alveolar crest into cementum of adjacent tooth)

Question 25

Unmineralized cementum is called what?

Answer 25

Cementoid

Question 26

Cementum is roughly _____ % inorganic and ______ % organic

Answer 26

50, 50

Question 27

Where are the main inorganic and organic components of cementum?

Answer 27

Inorganic: Hydroxyapetite Organic: 90% collagen type I, also some Type III and XII and other non collagenous proteins

Question 28

Where do cementoblasts originate from?

Answer 28

Dental follicle cells *Either induced by HERS or Dentin, or HERS itself becomes cementoblasts

Question 29

At the Cementoenamel junction, _____% of the time there is an overlap, _____% they meet up and ______% there is a gap

Answer 29

60, 30, 10

Question 30

What are the two general subtypes of cementum?

Answer 30

1-Acellular (primary) | 2-Cellular (secondary)

Question 31

What are the two collagen fiber origins for the cementum?

Answer 31

1-Extrinsic (from the PDL, come perpendicular) | 2-Intrinsic (come from the cementoblasts, parallel)

Question 32

Acellular extrinsic fiber cementum (AEFC) or Primary cementum covers what portion of the root?

Answer 32

Coronal 2/3 *Cellular intrinsic fiber cementum (CIFC) or secondary cementum covers the apical 1/3

Question 33

What type of dentin is formed by cementoblast processes called a fibrous fringe?

Answer 33

AEFC (acellular extrinsic fiber cementum) *after 15-20 um collagen synthesis stops and non-collagenous protein is produced to induce mineralization

Question 34

Collagen fibers from the developing PDL fibroblasts merge with the fibrous fringe and mineralize in place forming what?

Answer 34

Sharpeys fibers

Question 35

When cemetoblasts become entrapped in the advancing cementum and become cemtocytes, what is being formed?

Answer 35

CIFC (cellular intrinsic fiber cementum) *inner cementoblasts are generally non-vital. Layering of AEFC and CIFC is also possible

Question 36

Which type of cementum has no cells inside, no cemented, slower deposition, more mineralized and functions to attach the PDL to cementum?

Answer 36

AEFC (acellular extrinsic fiber cementum)

Question 37

Which type of cementum is more laminar, encapsulates cells, has visible cementoid, is often absent in canines and incisors and functions to adapt and adjust for wear as well as some attachment?

Answer 37

CIFC

Question 38

Recently confirmed, what kind of cementum is between granular layer of tomes and dental cementum proper, has a high mineralization and may function to seal the surface of root dentin?

Answer 38

Intermediate cementum

Question 39

What kind of cementum has alternating layers of AEFC and CIFC, has both extrinsic and intrinsic fibers, and is generally located apically?

Answer 39

Mixed cementum

Question 40

The abnormal thickening of cementum that can result in ankylosis is called what?

Answer 40

hypercementosis

Question 41

What are the 5 main tooth movements?

Answer 41

``` 1-tipping 2-Bodily 3-Extrusive 4-Intrusive 5-Rotational ```

Question 42

What are 3 facts that determine the degree of the effect of applied force?

Answer 42

1-transduction (conversion of physical force into biological, cannot be controlled) 2-Time (can be controlled) 3-Magnitude (can be controlled)

Question 43

What are 4 net results of tooth movements?

Answer 43

1-Compression 2-Tension 3-Hyalinization (loss of cell activity and vascularity due to too great or rapid of a compression) 4-Undermining resorption (in conjugation with hyalinization usually on opposite surface of compressed bone)