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Flashcards in odontogenesis Deck (45):
1

define odontogenesis

formation of tooth tissues from stem cells originating in the ectoderm primary germ layer

2

when does odontogenesis begin

6th week

3

the ectoderm germ layer splits into what basic tissues

mesenchyme and epithelium (and then the development into specific tooth tissues)

4

2 stages of odontogenesis

epithelial and tooth germ

5

primary dental lamina stage

starts in the 6th week as 2 epithelial invaginations (first in the lower jaw and then in the upper jaw). these invaginations descend into the underlying mesenchymal tissue/ectomesenchyme and move posteriorly.

6

facial band in the primary dental lamina stage=

vestibular lamina

7

lingual band in the primary dental lamina stage=

primary dental lamina

8

vestibular lamina fate

cell death occurs in the center of the band to create the VESTIBULE space

9

primary lamina fate

it is ODONTOGENIC and become the odontogenic epithelial part of a tooth germ

10

epithelial bud stage

primary dental lamina cells will develop into an epithelial bud aka primary buds (surrounded by mesenchyme/ectomesenchyme). the epithelial bud is continuous with the primary dental lamina still.

11

time of primary bud appearance of the primary central incisors

6 wks in utero

12

time of primary bud appearance of the primary second molars

8 wks in utero

13

time of permanent bud appearance of the first molar

4 mo in utero

14

time of permanent bud appearance of the central incisor

5 mo in utero

15

time of permanent bud appearance of the second molar

10 mo postnatally

16

time of permanent bud appearance of the third molar

5 years postnatally

17

how many primary buds are in each arch

10

18

how many total buds arise from the primary dental lamina

16 in each arch (10 primary and 6 permanent molars)

19

where do succedaneous teeth arise from

their own secondary dental lamina that arises from the lingual side of the primary dental lamina

20

how many succedaneous teeth are there

10 in each arch

21

where do non-succedaneous teeth arise from

their own bud off the primary dental lamina

22

epithelial cap stage

the epithelial buds form into epithelial caps

23

what is in the 'enamel knot'

concentration of epithelial cells in the center of the epithelial cap. acts as a signalling center to determine whether a tooth will develop to become an anterior or posterior tooth.

24

epithelial bell stage

epithelial cap grows/develops into an enamel organ (bell-shaped epithelial structure).

25

what are the 4 layers to an enamel organ

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

26

what is the white material in the stellate reticulum layer of the enamel organ

glycoprotein

27

what cells are derived from the inner epithelial layer

ameloblasts (form enamel)

28

where does the secondary dental lamina arise from

the primary dental lamina...lingual to it. remember there is a secondary dental lamina for each succedaneous tooth so there are 10 in each arch

29

4 stages of the epithelial stage of odontogenesis

1. epithelial dental lamina stage
2. epithelial bud stage
3. epithelial cap stage
4. epithelial bell stage (enamel organ)

30

what is the tooth germ stage

development of the epithelium and the mesenchymal tissues. cells of these tissues become formative cells of dentin, enamel, cementum, and pulp tissues.

31

what is a tooth germ

epithelial enamel organ and the closely associated ectomesenchymal tissue

32

3 parts of the tooth germ

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

33

what is the fate of the enamel organ

inner epithelial cells--> ameloblasts

34

is the enamel organ vascular or avascular

avascular

35

what is the structure called that is the result of all the layers of the enamel organ coming/merging together after the formation of enamel

reduced enamel epithelium...a stratified epithelial layer

36

what is the purpose of the reduced enamel epithelium

protect the enamel from surrounding connective tissue until the tooth enters the oral cavity

37

what is the fate of the dental papilla

starts off as mesenchymal cells that become odontoblasts (create dentin), fibroblasts, and reserve cells. ultimately becomes the pulp tissue!

38

is the dental papilla vascular or avascular

vascular

39

what is the fate of the dental follicle

starts off as mesenchymal cells that become cementoblasts, fibroblasts, osteoblasts, and reserve cells (stem cells). ultimately becomes the periodontal ligament of the periodontium.

40

is the dental follicle vascular or avascular

vascular

41

through what structure is the enamel organ attached to the mesenchyme (papilla and follicle)

basal lamina

42

the light acellular layer b/w the ameloblasts (in the inner epithelial layer) and the odontoblasts (in the dental papilla) is the future site of what

the dentinoenamel junction (DEJ)

43

what is the cervical loop

a double epithelial layer at the base of the enamel organ where the outer and inner epithelial layers meet

44

what is the double epithelial layer at the cervical loop called

hertwig's epithelial root sheath

45

what is the purpose of herwig's epithelial root sheath

1. determines root dentin outline
2. determines number of root canals a tooth has