Odontogenesis

Question 1

What are the four epithelial stages of Odontogenesis?

Answer 1

dental lamina
bud
cap
bell

Question 2

In the tooth germ stage, odontogenic ___ and ___ tissues combine to form cell of dentin, enamel, cementum, and pulp.

Answer 2

epithelial; mesenchymal

Question 3

During the 6th embryonic week, what two epithelial invaginations appear in the lower anterior region of the lower jaw an the upper jaw?

Answer 3

vestibular lamina

primary dental lamina

Question 4

The vestibular lamina and the primary dental lamina descend into the underlying mesenchymal tissue (___) and continue posteriorly within the mesenchyme as continuous epithelial bands.

Answer 4

ectomesenchyme

Question 5

The facial band is called ___ ___ and the lingual band is called ___ ___.

Answer 5

vestibular lamina; primary dental lamina

Question 6

In the vestibular lamina, cell ___ will occur in the center leaving a space known as the ___.

Answer 6

death; vestibule

Question 7

Cells arising from the dental laminae (primary and secondary) become the odontogenic ___ part of the tooth ___.

Answer 7

epithelial; germ

Question 8

Cells at the ___ (shallow/deep) end of the dental lamina, where a ___ is destined to form, will develop into epithelial knobs known as ___ ___.

Answer 8

deep; tooth; epithelial buds

Question 9

T/F. Each epithelial bud is surrounded by mesenchymal tissue.

Answer 9

True.

Question 10

The primary buds from within weeks ___ to ___ in utero. The central incisors form at week ___ and the second ___ form at week 8.

Answer 10

6; 8; 6; molars

Question 11

The permanent buds form from ___ months in utero to ___ years postnatally. The first ___ start to develop at 4 months and the central incisors at ___ month in utero. The second and third molars develop ___ months and ___ years postnatally.

Answer 11

4; 5; molar; 5; 10; 5

Question 12

A total of ___ epithelial buds arise from the primary dental lamina of each arch; ___ primary teeth and ___ permanent molars.

Answer 12

16; 10; 6

Question 13

Each ___ tooth has its own secondary dental lamina that arises from the ___ side of the primary dental lamina.

Answer 13

succedaneous; lingual

Question 14

A condensation of ___ is associated with the epithelial cap.

Answer 14

ectomesenchyme

Question 15

The site of the ___ ___ is a concentration of epithelial cells of the cap that acts as as ___ center and determines if the tooth will develop into an anterior or posterior tooth.

Answer 15

enamel knot; signaling

Question 16

T/F. The epithelial bell undergoes growth and develops into a cap shaped epithelial structure called an enamel organ.

Answer 16

False, The epithelial CAP undergoes growth and develops into a BELL shaped epithelial structure called an enamel organ.

Question 17

At the bell stage, what is arranged into 4 distinct cell layers?

Answer 17

the epithelium

Question 18

The secondary dental lamina is ___ to the primary tooth germ.

Answer 18

lingual

Question 19

How many secondary lamina arise in each arch?

Answer 19

Ten, one for each secondary tooth

Question 20

The secondary dental lamina arises from the ___ ___ ___ not the ___ epithelium.

Answer 20

primary dental lamina; oral

Question 21

What are the three distinct parts of the tooth germ?

Answer 21

1. enamel organ
2. dental papilla
3. dental follicle

Question 22

T/F. The enamel organ and dental papilla consist of epithelium and the dental follicle contains mesenchyme (ectomesenchyme).

Answer 22

False, the enamel organ ONLY consist of epithelium and the dental follicle AND dental papilla contains mesenchyme (ectomesenchyme).

Question 23

What part of the tooth germ is avascular? vascular?

Answer 23

avascular - enamel organ

vascualr - dental papilla and follicle

Question 24

What do inner epithelial cell differentiate into?

Answer 24

ameloblasts - specialized epithelial cells

Question 25

After the formation of enamel is complete, the ameloblasts, along with other layers of the enamel organ come together over the surface of the enamel as a ___ structure called the ___ ___ epithelium.

Answer 25

protective; reduced enamel

Question 26

The dental ___ has undifferentiated cells (stem cells) that become odontoblast, ___ and reserve cells.

Answer 26

papilla; fibroblast

Question 27

What part of the tooth germ ultimately becomes the pulp tissue of the tooth?

Answer 27

dental papilla

Question 28

Which part of the tooth germ has stem cells that become cementoblast, fibroblast, osteoblast, and reserve cells?

Answer 28

dental follicle

Question 29

The dental follicle ultimately becomes the ___ ___ of the periodontium.

Answer 29

periodontal ligament

Question 30

What structure attaches the enamel organ to both mesenchymal parts of the tooth germ?

Answer 30

basal lamina

Question 31

T/F. Ameloblast appear as columnar epithelial cells.

Answer 31

True.

Question 32

The light, ___ layer between odontoblasts and ameloblasts is the site of the future ___ junction.

Answer 32

acellular; dentinoenamel

Question 33

The ameloblast start near the dentin and move outward toward the ___ ___ epithelial layer.

Answer 33

stratum intermedium

Question 34

What are the four distinct epithelial cell layers of the enamel organ?

Answer 34

1. inner epithelial layer
2. stratum intermedium epithelial layer
3. stellate reticulum epithelial layer
4. outer epithelial layer

Question 35

What is the role of the reduced enamel epithelium?

Answer 35

it protects the enamel from surrounding connective tissue until the tooth enters the oral cavity.

Question 36

What is the rim of the epithelial bell (enamel organ) where the inner and outer cell layers merge called?

Answer 36

cervical loop

Question 37

When the inner and outer cell layers come together at the cervical loop it forms a ___ epithelial layer called the ___ ___ ___ ___.

Answer 37

double; Hertwig’s epithelial root sheath

Question 38

What are the two main funcitons of the Hertwig’s epitheal root sheath?

Answer 38

1. determines root dentin outline

2. determines number of root canals of tooth