Odontogenesis

Question 1

From what type of cells do tooth tissues derive from?

Answer 1

Stem cells originating in the ectoderm primary germ layer

Question 2

When does odontogenesis occur?

Answer 2

6th embryonic week

Question 3

What two tissues from the ectoderm are involved in odontogenesis?

Answer 3

Epithelium and mesenchyme

Question 4

Dentinogenesis

Answer 4

Formation of dentin

Question 5

Amelogenesis

Answer 5

Formation of enamel

Question 6

Cemetogenesis

Answer 6

Formation fo cementum

Question 7

What are the epithelial stages based on

Answer 7

Histological shapes of the epithelial tissue within a mesenchymal environment

Question 8

What are the epithelial stages of tooth development?

Answer 8

Epithelial dental lamina stage
Epithelial bud stage
Epithelial cap stage
Epithelial bell stage

Question 9

At what stage is the epithelium is arranged in 4 distinct cell layers

Answer 9

Epithelial bell stage

Question 10

What happens during the tooth germ stage

Answer 10

Odontogenic epithelial and mesenchymal tissues are combined

Cells of each tissue is induced specifically to become fomative cells of dentin, enamel, cementum, and pulpal tissues

Question 11

What tissue does the enamel organ derive from?

Answer 11

Epithelium

Question 12

What tissue does the dental papilla drive from?

Answer 12

Mesenchyme

Question 13

What tissue does the dental follicle derive from?

Answer 13

Mesenchyme

Question 14

What occur during the primary dental lamina stage

Answer 14

Two epithelial invaginations appear in the lower anterior region of the lower jaw and later in the same week (6th) in the upper jaw
The invaginations descend into the underlying mesenchymal tissue (ectomesenchyme) and continue posteriorly within the mesenchyme as continuous epithelial bands

Question 15

What are the 2 invaginations of the primary dental lamina stages?

Answer 15

Vestibular lamina

Primary dental lamina

Question 16

Vestibular lamina

Answer 16

Facial band of invagination during primary dental lamina stage
Cell death will occur in the center of the vestibular lamina, leaving space known as the ‘vestibule’

Question 17

Primary dental lamina

Answer 17

Lingual band of invagiation during primary dental lamina stage
Cells arising form the dental laminae (primary and secondary) become odontogenic epithelial part of tooth germ

Question 18

Epithelial bud stage

Answer 18

Cells at the deep end of the dental lamina develop into epithelial knobs, known as ‘epithelial bud’
Each bud is surrounded by mesenchymal tissue, and bud cells are continuous with cells of the primary dental lamina

Question 19

When do primary buds form?

Answer 19

6-8 weeks in utero

Question 20

When do permanent buds form?

Answer 20

4 months in utero to 5 years postnatal

Question 21

When do primary central incisor buds form?

Answer 21

6 weeks in utero

Question 22

When do primary second molar buds form?

Answer 22

8 weeks in utero

Question 23

When do first molar permanent buds form?

Answer 23

4 months in utero

Question 24

When do permanent central incisor buds form?

Answer 24

5 months in utero

Question 25

When do permanent second molar buds form?

Answer 25

10 months postnatally

Question 26

When do permanent third molar buds form?

Answer 26

5 years postnatally

Question 27

Epithelial cap stage

Answer 27

Odontogenic epithelial is in the shape of the cap | -this cap used to be the epithelial bud

Question 28

Enamel knot

Answer 28

Concentration of epithelial cells in the epithelial cap | Signaling center to determine if the tooth will develop to become an anterior or posterior tooth

Question 29

Epithelial bell stage

Answer 29

Epithelial cap undergoes growth and develops into a bell shaped epithelial structure called the 'enamel organ' Epithelium is in 4 distinct layers

Question 30

What are the 4 cell layers of the epithelial bud stage?

Answer 30

Inner epithelial layer Stratum intermedium epithelial layer Stellate reticulum epithelial layer Outer epithelial layer

Question 31

What layer of the epithelial bell becomes the ameloblasts?

Answer 31

Inner epithelial layer

Question 32

Secondary dental lamina

Answer 32

Lingual to the primary tooth germ | Arises from the primary dental lamina - not the oral epithelium

Question 33

How many secondary lamina arise in each arch?

Answer 33

10 - one for each secondary tooth

Question 34

Tooth germ stage

Answer 34

The epithelial enamel organ and a closely associated ectomesenchymal tissue that is continuous form around the epithelium to within the epithelium -when combined, the enamel organa and ectomesenchyme are a tooth germ

Question 35

What are the 3 parts of the tooth germ?

Answer 35

Enamel organ Dental papilla Dental follicle

Question 36

Enamel organ

Answer 36

Avascular tissue from epithelium | inner epithlial cells differentiate into ameloblasts

Question 37

After formation of the enamel is complete, ameloblasts, along with the other layers of the enamel organ come together to form what?

Answer 37

Reduced enamel epithelium

Question 38

What is the purpose of the reduced enamel epthelium?

Answer 38

It is a protective structure over the surface of the enamel until the tooth enters the oral cavity

Question 39

Dental papilla

Answer 39

Vascular tissue form mesenchyme Stem cells become odontoblasts, fibroblasts, and reserve cells Ultimately becomes the pulp of the tooth

Question 40

Dental follicle

Answer 40

Vascular tissue from mesenchyme Stem cells become cementoblasts, fibroblasts, osteoblasts, and reserve cells Ultimately becomes the periodontal ligament of the periodontium

Question 41

Where is the initial site of appearance of ameloblasts and odontoblasts?

Answer 41

Within the tooth germ along the area between the papilla and the inner cells of the enamel organ

Question 42

Ameloblasts form what?

Answer 42

Enamel

Question 43

Odontobalsts form what?

Answer 43

Dentin

Question 44

What is the fate of enamel organ cells after completion of enamel?

Answer 44

The 4 cell layer come together to form the reduced enamel epithelium

Question 45

Cervical loop

Answer 45

Rim of the epithelial bell | This is the site where the inner and outer cells merge

Question 46

Fate of the cervical loop

Answer 46

Outer and inner layers come together to form a double epithelial layer called 'Hertwig's epithelial root sheath'

Question 47

Hertwig's epitheliual root sheath

Answer 47

Determines the root-dentin outline | Determines the number of root canals of the tooth