odontogenesis

Question 1

two basic tissues that arise from the ectoderm primary germ layer involved in tooth development:

Answer 1

epithelium and mesenchyme

Question 2

odontogenesis begins in the ____ embryonic week

Answer 2

6th

Question 3

epithelial stages of odontogenesis

Answer 3

1. epithelial dental lamina stage
2. epithelial bud
3. epithelial cap
4. epithelial bell

Question 4

3 parts of the tooth germ

Answer 4

1. enamel organ (bell): epithelium
2. dental papilla: mesenchyme
3. dental follicle: mesenchyme

Question 5

facial band is called the ____

Answer 5

vestibular lamina

Question 6

lingual band is called the _____

Answer 6

primary dental lamina

Question 7

cell death will occur in the center of the vestibular lamina, leaving a space known as the _____

Answer 7

vestibule

Question 8

cells arising from the dental laminae become the _____ part of a ____

Answer 8

odontogenic epithelial; tooth germ

Question 9

appearance times for epithelial buds of primary central incisors and second molars

Answer 9

central incisors: 6 weeks in utero

second molars: 8 weeks in utero

Question 10

appearance times for epithelial buds of permanent central incisiors, 1st/2nd/3rd molars:

Answer 10

first molar: 4 months in utero
1st molar: 5 months in utero
second molar: 10 months postnatally
third molar: 5 years postnatally

Question 11

a total of ____ epithelial buds arise from the ____ of each arch

Answer 11

16; primary dental lamina

10 primary teeth and 6 permanent molars

Question 12

each primary tooth also has its own ____ that arises from ____ of the primary dental lamina

Answer 12

secondary dental lamina; lingual side

Question 13

concentration of epithelial cells of cap that is a signaling center

Answer 13

enamel knot

Question 14

what does the enamel knot determine?

Answer 14

whether the tooth will become an anterior or posterior tooth

Question 15

at the bell stage, the epithelium is arranged in ____ distinct cell layers

Answer 15

4

Question 16

4 distinct epithelial cell layers of the enamel organ

Answer 16

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

Question 17

secondary dental lamina is ____ to the primary tooth germ; ____ secondary lamina arise in each arch, one for each secondary tooth

Answer 17

lingual; ten

Question 18

secondary dental lamina arise from the _____, NOT the oral epithelium

Answer 18

primary dental lamina

Question 19

the enamel organ is composed of:

Answer 19

epithelial enamel organ + closely associated ectomesenchyme

Question 20

3 distinct parts of the enamel organ

Answer 20

1. enamel organ (epithelium- avascular)
2. dental papilla (ectomesenchyme- vascular)
3. dental follicle (ectomesenchyme- vascular)

Question 21

inner epithelial cells differentiate into ____- specialized epithelial cells

Answer 21

ameloblasts

Question 22

after formation of enamel is complete, ameloblasts, along with other layers of the enamel organ, come together over the surface of the enamel as a ____ structure called _____

Answer 22

protective; reduced enamel epithelium (it is a stratified epithelial layer)

Question 23

undifferentiated cells (stem cells) of the dental papilla become:

Answer 23

odontoblasts, fibroblasts (most numerous), and reserve cells

Question 24

the dental papilla ultimately becomes the _____

Answer 24

pulp tissue of the tooth

Question 25

the stem cells of the dental follicle become:

Answer 25

cementoblasts, fibroblasts (most numerous), osteoblasts, and reserve cells

Question 26

the dental follicle ultimately becomes the _____

Answer 26

periodontal ligament of the periodontium

Question 27

the enamel organ is attached to both mesenchymal parts of the tooth germ by a _____

Answer 27

basal lamina

Question 28

the light, acellular layer between odontoblasts and ameloblasts is the site of the future _____

Answer 28

dentinoenamel junction (DEJ)

Question 29

the rim of the epithelial bell (enamel organ) where inner and outer cell layers merge or meet

Answer 29

cervical loop

Question 30

the double epithelial layer of the cervical loop is called ______

Answer 30

Hertwig's epithelial root sheath

Question 31

2 main functions of the root sheath

Answer 31

1. determines root dentin outline | 2. determines number of root canals of tooth

Question 32

the pulp is formed from what part of the tooth germ and what two formative (blast) cell types arose from its stem cells?

Answer 32

dental papilla | odontoblasts and fibroblasts

Question 33

the periodontal ligament is formed from what part of the tooth germ and what 3 formative (blast) cell types arose from its stem cells?

Answer 33

dental follicle | fibroblasts, cementoblasts, and osteoblasts