odontogenesis

Question 1

define odontogenesis

Answer 1

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

Question 2

when does odontogenesis begin

Answer 2

6th week

Question 3

the ectoderm germ layer splits into what basic tissues

Answer 3

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

Question 4

2 stages of odontogenesis

Answer 4

epithelial and tooth germ

Question 5

primary dental lamina stage

Answer 5

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.

Question 6

facial band in the primary dental lamina stage=

Answer 6

vestibular lamina

Question 7

lingual band in the primary dental lamina stage=

Answer 7

primary dental lamina

Question 8

vestibular lamina fate

Answer 8

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

Question 9

primary lamina fate

Answer 9

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

Question 10

epithelial bud stage

Answer 10

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.

Question 11

time of primary bud appearance of the primary central incisors

Answer 11

6 wks in utero

Question 12

time of primary bud appearance of the primary second molars

Answer 12

8 wks in utero

Question 13

time of permanent bud appearance of the first molar

Answer 13

4 mo in utero

Question 14

time of permanent bud appearance of the central incisor

Answer 14

5 mo in utero

Question 15

time of permanent bud appearance of the second molar

Answer 15

10 mo postnatally

Question 16

time of permanent bud appearance of the third molar

Answer 16

5 years postnatally

Question 17

how many primary buds are in each arch

Answer 17

10

Question 18

how many total buds arise from the primary dental lamina

Answer 18

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

Question 19

where do succedaneous teeth arise from

Answer 19

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

Question 20

how many succedaneous teeth are there

Answer 20

10 in each arch

Question 21

where do non-succedaneous teeth arise from

Answer 21

their own bud off the primary dental lamina

Question 22

epithelial cap stage

Answer 22

the epithelial buds form into epithelial caps

Question 23

what is in the ‘enamel knot’

Answer 23

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.

Question 24

epithelial bell stage

Answer 24

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

Question 25

what are the 4 layers to an enamel organ

Answer 25

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

Question 26

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

Answer 26

glycoprotein

Question 27

what cells are derived from the inner epithelial layer

Answer 27

ameloblasts (form enamel)

Question 28

where does the secondary dental lamina arise from

Answer 28

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

Question 29

4 stages of the epithelial stage of odontogenesis

Answer 29

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

Question 30

what is the tooth germ stage

Answer 30

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

Question 31

what is a tooth germ

Answer 31

epithelial enamel organ and the closely associated ectomesenchymal tissue

Question 32

3 parts of the tooth germ

Answer 32

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

Question 33

what is the fate of the enamel organ

Answer 33

inner epithelial cells--> ameloblasts

Question 34

is the enamel organ vascular or avascular

Answer 34

avascular

Question 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

Answer 35

reduced enamel epithelium...a stratified epithelial layer

Question 36

what is the purpose of the reduced enamel epithelium

Answer 36

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

Question 37

what is the fate of the dental papilla

Answer 37

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

Question 38

is the dental papilla vascular or avascular

Answer 38

vascular

Question 39

what is the fate of the dental follicle

Answer 39

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

Question 40

is the dental follicle vascular or avascular

Answer 40

vascular

Question 41

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

Answer 41

basal lamina

Question 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

Answer 42

the dentinoenamel junction (DEJ)

Question 43

what is the cervical loop

Answer 43

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

Question 44

what is the double epithelial layer at the cervical loop called

Answer 44

hertwig's epithelial root sheath

Question 45

what is the purpose of herwig's epithelial root sheath

Answer 45

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