Lecture 10- Periodontium (foster)

Question 1

An extension of enamel organ, transforms from the cervical loop. It is a bilayer of IEE and OEE

Answer 1

hertwigs root sheath

Question 2

What are the functions of hertwigs sheath

Answer 2

• “architect” of the root defining size and shape (morphogenesis)
• induces root odontoblast differentiation

Question 3

The … and …. of roots DEPENDS on HERS cell … and…

Answer 3

• size and shap

- migration and proliferation

Question 4

What are the processes called of HERS that are referred to as tongues that grow toward one another

Answer 4

epithelial interradicular processes

Question 5

HERS induces …. cells to differentiate to pre-odontoblasts and then odontoblasts

Answer 5

dental papilla cells

Question 6

…. forms in step with HERS proliferation

Answer 6

root dentin

Question 7

is HERS permanent or transient?

Answer 7

transient

Question 8

Some HERS cells become …

Answer 8

epithelial rests of Malassez (ERM)

Question 9

HERS disintegrates shortly after…

Answer 9

inducing root odontoblast differentiation

Question 10

… appear as clumps, strands or network of cells in the PDL and are surrounded by a basement membrane. Sometimes are close to the root and sometimes several layers away

Answer 10

ERM (epithelial rests of Malassez)

Question 11

… can cause cysts. They are speculated to be involved with PDL homeostasis or regeneration but it is not proven

Answer 11

ERM (epithelial rests of Malassez)

Question 12

root dentin comes from … cells

Answer 12

ectomesenchyme

Question 13

dentinogenesis of root is largely the same as crown dentin except interacts with IEE of…. instead of….

Answer 13

• HERS

- IEE of enamel organ

Question 14

Mouse example:
epithelial-mesenchymal signaling in the root starts in … with the … TF which secretes signal called…. (paracrine kind of signal) and that signal goes to …. cells which then induces …. TF and then downstream the…. TF which causes odontoblast differentiation

Answer 14

• HERS
• Smad4
• Sonic hedgehog (SHH)
• papilla
• Gli1
• Nfic

Question 15

Mouth example:
Without Nfic TF, the dental papilla cannot respond to…. and cells do not differentiate into odontoblasts which causes rootless teeth

Answer 15

HERS signaling

Question 16

3 development root defects

Answer 16

1. rootless teeth
2. dilaceration
3. taurodontism

Question 17

…. is when there is a large pulp chamber at the expense of the root/furcation

Answer 17

taurodontism

Question 18

…. is a deformity in shape/direction of root

Answer 18

dilaceration

Question 19

cementum comes in … main types. these types are defined by the presence/absence of cells within its…. and the origin of ….

Answer 19

• 2
• matrix
• collagen fibers of the matrix

Question 20

2 major types of cementum

Answer 20

acellular cementum

cellular cementum

Question 21

acellular cementum is also called… or…

Answer 21

• Acellular extrinsic fiber cementum (AEFC)

- primary cementum

Question 22

cellular cementum is also called…. or …

Answer 22

• cellular intrinsic fiber cementum

- secondary cemntum

Question 23

the primary acellular cementum covers …. of the root

Answer 23

2/3

Question 24

the secondary cellular cementum covers the…. of the root

Answer 24

apical 1/3

Question 25

2 minor types of cementum

Answer 25

1. acellular afibrillar cementum (AAC) | 2. Cellular mixed stratified cementum (CMSC)

Question 26

AAC is present right by the...

Answer 26

CEJ

Question 27

.... is a mix of alternating acellular and cellular layers or cementum in the root

Answer 27

CMSC

Question 28

4 functions of the cementum

Answer 28

1. attachment- acellular mainly 2. Protects- root resorption/ repairs resorption pits 3. Adjusts tooth position (cellular only) 4. Seals dentin tubules

Question 29

cementum composition

Answer 29

- 50% inorganic/HA - 35% organic (90% type 1) - 15% water

Question 30

3 characteristics of cementum physiology which are different from bone

Answer 30

1. avascular 2. non-innervated 3. no turnover- growth by apposition

Question 31

classic hypothesis for origin of cementum

Answer 31

ectomesenchyme dental follicle cells cementoblast

Question 32

functions of cementoblasts

Answer 32

make acellular and cellular cementum

Question 33

fate of cementoblasts

Answer 33

remain in PDL close to cementum surface, regulate slow cementum growth through life, direct cementum repair

Question 34

origin of cementoblasts

Answer 34

from dental follicle (ectomesenchyme)

Question 35

Products of cementoblasts

Answer 35

1. collagen 2. ECM proteins 3. enzymes that promote cementum mineralization

Question 36

... are a subset of cementoblasts that become embedded in the cellular cementum matrix (so origin is follicle/ectomesenchyme)

Answer 36

cementocytes

Question 37

Extrinsic fibers are continuity of extrinsic fibers and initial intrinsic fibers and they will become mineralized .... within cementum

Answer 37

Sharpey's fibers

Question 38

.... produce primary collagen fiber bundles of PDL space and are stitched to first cementum intrinsic fibers

Answer 38

PDL fibroblasts

Question 39

Extrinsic fibers (sharpeys fibers) are the MAJOR fiber group for

Answer 39

acellular cementum

Question 40

Extrinsic fibers (sharpeys fibers) enter acellular cementum at ..

Answer 40

high density

Question 41

Extrinsic fibers (sharpeys fibers) are critical to the .... of the acellular cementum

Answer 41

function