Root formation/Advanced bell stage

Question 1

area where IEE and OEE meet is called

Answer 1

cervical loop

Question 2

cervical loop gives rise to

Answer 2

root sheath

Question 3

once the crown is formed the cervical loop gives rise to

Answer 3

hertwigs epithelial root sheath

Question 4

at the begining the root sheath……….. towards the

Answer 4

bends at a angle of 45 degrees/ towards the pulp

Question 5

The bending of the root sheath is benfically because it….. this is called the ……. and will eventually become…..

Answer 5

narrows the wide cervical opening of the crown

epithelial diaphragam

apical foramen

Question 6

Hertwig’s Epithelial Root Sheath is…..

the epithelial diaphragm……..

Answer 6

a bilayer of epithelial cells covering the connective tissue of the developing root.

is the part of the HERS underneath the developing crown.

Question 7

what cause the root to grow…

Hint :Proliferation

Answer 7

-Proliferation of the epithelial cells of the cervical loop by mitosis, growth is located in the region of the cervical margin of the crown, this creates a epithelial sheath, which bends inwards to form hertwigs epitheial root sheath

Question 8

Label the diagram

Answer 8

Question 9

the Elongation of HERS

Answer 9

• The lateral edges of HERS also undergoes cell division
• The newly formed cells form an epithelial layer on the lateral surface of the developing root

Question 10

HERS is a bilayer cellular structure:

composities of a …… facing the ……

and a ……. facing the…..

Answer 10

IEE/ dental pappila

OEE/ Dental folicles

Question 11

The apical bent portion of the HERS is named:

Its role:

For this to happen:

This results in:

Next:

making contact:

Answer 11

epithelial diaphragm

to induce dentinogenesis (making dentin)

the diaphragm send induction messages to the ectomescyn cells of the dental pappila

The fromation of odontoblasts

Secrect mantle dentin

with IE cells of the rooth sheath

Question 12

Hertwig’s epithelial root sheath (HERS) is ……

Answer 12

a bilayer of epithelial cells that induces differentiation of dental papilla cells into root odontoblasts.

Question 13

Once root dentin is formed, HERS

and the cells of the inner layer of the

and differentiate into

Cells of the outer layer of the dental follicle differentiate into ……..and ………..that, together with…………, contribute to periodontium formation.

Answer 13

loses continuity

dental follicle (mesenchymal cells surrounding the tooth germ) come into contact with the root dentin

cementoblasts.

fibroblasts / osteoblasts/ cementoblasts

Question 14

Once dentin is layed out

along the dentin matrix that is now formed, the cells of the ……… ……… …….

leaving only…….

The cells of this sheath then synthesis and …………

Then they…

Answer 14

outer epithelial layer disintergrate

Inner epithelial layer

release enamel related proteins

detach from the root surface

Question 15

The mantel dentine and enamel related protien comes into contact with

inducing….

Cells differentiation into either……. that ……………….

or into ……………. that………….

Answer 15

dental follicles

Cementogenesis

fibroblast cells/ migrate towards the root surface with a perpendicular orentations

cemontenblasts/ face parallel to the surface of the tooth

Question 16

fibrobasts create the ……………

cementoblasts…………….

Answer 16

extrinsic fibers

instrinsic fibers

Question 17

Making Multirooted Teeth

Answer 17

• HERS undergoes focal mitotic activity, forming ridges of epithelium that proliferate centrally
• These Epithelial Diaphragms fuse near midline of tooth, forming 2-3 roots
• These diaphragms also cause odontoblastic differentiation leading to root dentin

Question 18

End of Root Formation

Leftove HERS cells….

what are they called…..

Function………

Answer 18

• HERS is stretched over surface of root, then indergoes partial degeneration
• Network of leftover HRS cells persist thoughout life within the periodontal ligament
• Look like clusters called the Epithelial Rests of Malassez
• These have no function but cysts and tumors can occur here