EX2; Periodontium Development

Question 1

What structures does the periodontium include

Answer 1

cementum
PDL
bony socket
gingiva facing the tooth; junctional and sulcular epithelium

Question 2

This is the calcified material that covers the root dentin

Answer 2

cementum

Question 3

This is largely composed to collagen fibers which are embedded on one end to the cementum and the other to the periodontium

Answer 3

PDL

Question 4

All but which structure serves a role in the attachment of the tooth

Answer 4

sulcular gingiva

Question 5

True or False

the tooth root develops after the crown

Answer 5

True

Question 6

What guides root growth

Answer 6

Hertiwig’s epithelial root sheath

Question 7

The initiation of root dentinogenesis slightly precedes what

Answer 7

periodontal development

Question 8

What is the inductive signal from HERS for odontoblast differentiation

Answer 8

TGF-β and/or laminin5

Question 9

Once dentin in the root begins to be laid down, what occurs

Answer 9

HERS separates from root dentin

osteobalsts, cementoblasts, PDL fibroblasts differentiate and migrate to their appropriate locations

Question 10

What is the order in which the blast cells secrete their substance

Answer 10

cementoblasts and osteoblasts secrete their organic matrix (type 1 collagen) first
PDL fibroblasts secrete their organic collagen matrix

Question 11

The organic matrices of cementum and bone are secreted before what begins

Answer 11

mineralization

Question 12

How does the PDL become entrapped in the cementum and bone

Answer 12

it intermingles with the unmineralized matrices and then is locked in during mineralization

Question 13

All of periodontal development is occurring as what is happening

Answer 13

the tooth is erupting

Question 14

What changes in orientation does the PDL undergo as the tooth is erupting

Answer 14

starts out in an oblique orientation with the end in the cementum apically, then it becomes more horizontal, then obliquely again with the cementum more coronal

Question 15

In which direction does the periodontium grow

Answer 15

from the CEJ to the root apex

Question 16

This type of cementum is mainly acellular and is located on the coronal 2/3 of the tooth

Answer 16

primary cementum

Question 17

This type of cementum is mainly cellular and located on the apical 2/3

Answer 17

secondary cementum

Question 18

When is secondary cementum formed

Answer 18

after at least half of the root is completed and about the time the tooth emerges from the oral cavity

Question 19

Which type of cementum is more important in serving an attachment function

Answer 19

primary cementum

Question 20

Along the advancing root edge, what is there a continuous layer of

Answer 20

predentin extending between the future DCJ and the pulp

Question 21

A little coronal to the developing root, the root dentin begins to mineralize, creating what

Answer 21

two separate unmineralized parts of dentin (predentin and non-mineralized dentin at the future DCJ)

Question 22

At what orientation to the DCJ are the cementum collagen “fiber fringe” laid down

Answer 22

right angles

Question 23

The cementum fiber fringe extends into what, then what occurs

Answer 23

extends into the unmineralized dentin matrix and upon mineralization the fiber fringe is embedded in the dentin matrix

Question 24

The firm attachment between the cementum and dentin is a consequence of what

Answer 24

the fact that collagen fibers of these two tissues intermingle prior to mineralization

Question 25

As primary cementum is laid down, cementoblasts do what

Answer 25

retreat toward the future PDL; they do not become entrapped in the forming matrix (hence, acellular)

Question 26

Fragmented HERS remain in the PDL as what

Answer 26

epithelial rests of Mallasez

Question 27

What are the similarities between the formation of primary and secondary cementum

Answer 27

similarity; formed in the same way regarding the fringe and dentin mingling prior to mineralization
difference; cementoblasts become trapped in the cementum matrix (hence, cellular)

Question 28

Sulcular epithelium arises from what

Answer 28

embryonic oral epithelium

Question 29

Junctional epithelium arises from what

Answer 29

reduced enamel epithelium

Question 30

The periodontium structures arise from which portion of the tooth germ

Answer 30

dental follicle

Question 31

There is a debate over this cell regarding of whether it came from ectomesenhyme (NCC) dental follicle or epithelial; HERS

Answer 31

cementoblasts

Question 32

What is the general consensus regarding the origin of cementoblasts

Answer 32

cementum-forming cells may be derived from both the dental follicle and HERS

Question 33

These are secreted growth factors implicated in cementoblast induction

Answer 33

BMPs; bone morphogenetic proteins

Question 34

These are transcription factors implicated in cementoblast differentiation

Answer 34

RunX

Question 35

These are extracellular matrix molecules implicated in cementogenesis

Answer 35

bone sialoprotein and osteopontin; both secreted from cementoblast about the same time as the initial collagen matrix; role in mineralization

Question 36

This is secreted by cementoblasts and plays a role in cementoblast adhesion to root dentin surface and cementum mineralization

Answer 36

bone sialoprotein (BSP)