Odontogenesis Flashcards Preview

Oral Histology > Odontogenesis > Flashcards

Flashcards in Odontogenesis Deck (47):
1

From what type of cells do tooth tissues derive from?

Stem cells originating in the ectoderm primary germ layer

2

When does odontogenesis occur?

6th embryonic week

3

What two tissues from the ectoderm are involved in odontogenesis?

Epithelium and mesenchyme

4

Dentinogenesis

Formation of dentin

5

Amelogenesis

Formation of enamel

6

Cemetogenesis

Formation fo cementum

7

What are the epithelial stages based on

Histological shapes of the epithelial tissue within a mesenchymal environment

8

What are the epithelial stages of tooth development?

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

9

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

Epithelial bell stage

10

What happens during the tooth germ stage

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

11

What tissue does the enamel organ derive from?

Epithelium

12

What tissue does the dental papilla drive from?

Mesenchyme

13

What tissue does the dental follicle derive from?

Mesenchyme

14

What occur during the primary dental lamina stage

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

15

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

Vestibular lamina
Primary dental lamina

16

Vestibular lamina

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'

17

Primary dental lamina

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

18

Epithelial bud stage

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

19

When do primary buds form?

6-8 weeks in utero

20

When do permanent buds form?

4 months in utero to 5 years postnatal

21

When do primary central incisor buds form?

6 weeks in utero

22

When do primary second molar buds form?

8 weeks in utero

23

When do first molar permanent buds form?

4 months in utero

24

When do permanent central incisor buds form?

5 months in utero

25

When do permanent second molar buds form?

10 months postnatally

26

When do permanent third molar buds form?

5 years postnatally

27

Epithelial cap stage

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

28

Enamel knot

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

29

Epithelial bell stage

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

30

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

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

31

What layer of the epithelial bell becomes the ameloblasts?

Inner epithelial layer

32

Secondary dental lamina

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

33

How many secondary lamina arise in each arch?

10 - one for each secondary tooth

34

Tooth germ stage

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

35

What are the 3 parts of the tooth germ?

Enamel organ
Dental papilla
Dental follicle

36

Enamel organ

Avascular tissue from epithelium
inner epithlial cells differentiate into ameloblasts

37

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

Reduced enamel epithelium

38

What is the purpose of the reduced enamel epthelium?

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

39

Dental papilla

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

40

Dental follicle

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

41

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

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

42

Ameloblasts form what?

Enamel

43

Odontobalsts form what?

Dentin

44

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

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

45

Cervical loop

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

46

Fate of the cervical loop

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

47

Hertwig's epitheliual root sheath

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