Chapter 6-1 Tooth development and Eruption

Question 1

Define odontogenesis

Answer 1

Process of tooth development

Question 2

What are the stages of tooth development (time frame)

Answer 2

1. Initiation: 6 - 7th week
2. Bud: 8th week
3. Cap: 9thweek
4. Bell: 12th week
5. Apposition: varies
6. Maturation: varies

Question 3

What are the main processes in each stage

Answer 3

1. Initiation: Induction
2. Bud: Proliferation
3. Cap: Proliferation, differentiation, morphogenesis
4. Bell: Proliferation, differentiation, morphogenesis
5. Apposition: Induction, proliferation
6. Maturation: maturation

Question 4

When does odontogenesis of primary dentition occur

Answer 4

6th and 7th week

Question 5

What occurs in the apposition stage?

Answer 5

Formation of partially mineralized dental tissue types, such as enamel, dentin, cementum (the hard tooth tissue)

Question 6

What occurs during maturation

Answer 6

Structures go through continued mineralization

Question 7

Induction

Answer 7

Active interaction between embryologic tissue types

Question 8

At the beginning of 6th week what occurs?

Answer 8

The embryo’s stomodeum is lined by ectoderm

Question 9

What does the outerpart of the ectoderm give rise to

Answer 9

oral epithelium

Question 10

How is the dental lamina formed

Answer 10

When oral epithelium grows deeper into the ectomesenchyme

Question 11

In what direction does the dental lamina grow

Answer 11

Starts in midline and progresses posteriorly

Question 12

What happens in the bud stage

Answer 12

• extensive proliferation of dental lamina into buds which penetrate the ectomesenchyme
• Proliferation of ectomesenchyme

Question 13

What does the cap stage involve

Answer 13

Proliferation and differentiation to form tooth germ and primordium of primary tooth

Question 14

What does the tooth germ consist of?

Answer 14

Enamel organ, dental papilla, dental sac

Question 15

What is the predominant process in cap stage

Answer 15

morphogenesis

Question 16

How is the dental papilla formed

Answer 16

ectomesenchyme in the concavity of the cap condenses into a mass

Question 17

What does the dental papilla give rise to

Answer 17

Dentin and pulp

Question 18

What is the dental sac/dental follicle?

Answer 18

remaining ectomesenchyme that surrounds the outside of the cap of enamel organ

Question 19

What does the dental sac produce

Answer 19

Periodontium
Supporting tissue types of the tooth
Cementum
Periodontal ligament
Alveolar process

Question 20

Tooth germ consist of:

Answer 20

Enamel organ
Dental papilla
Dental sac

Question 21

What does the enamel organ…
Arise from?
Origin?
Give rise to?
Description

Answer 21

Arises from oral ectoderm and dental lamina
Epithelial origin
Gives rise to enamel
Develops different layers during cap and bell stages of development

Question 22

What does Dental Papilla…
Arise from?
Origin
Give rise to?
Description

Answer 22

Arises from ectomesenchyme
Connective tissue origin
Forms dentin and pulp
A condensed zone of cells beneath enamel organ and separated from by a basement membrane

Question 23

What does the Dental sac (Follicle)…
Arise from?
Origin
Give rise to?
Description

Answer 23

Arises from ectomesenchyme
Connective tissue origin
Form cementum, periodontal ligament, alveolar bone
Fibrous tissue

Question 24

What are the 4 cell types that occur during bell stage

Answer 24

Outer enamel epithelium
Stellate reticulum
Stratum intermedium
Inner enamel epithelium

Question 25

What cells make up the outer enamel epithelium?

Answer 25

Cuboidal cells of enamel organ

Question 26

What cells makes up the inner enamel epithelium?

Answer 26

Tall Columnar cells

Question 27

What type of cells is the stellate reticulum

Answer 27

start shaped cells

Question 28

What type of cells is the stratum intermedium

Answer 28

compressed flat to cuboidal cells

Question 29

What are the 2 layers of dental papilla histodifferentiation

Answer 29

1. outer cells of dental papilla 2. Central cells of dental papilla

Question 30

Outer cells of dental papilla become...

Answer 30

dentin secreting odontoblasts

Question 31

Central cells of the dental papilla become...

Answer 31

Promordium of dental pulp

Question 32

Dental sac undergoes histodifferentation _____(later than /before) enamel organ and dental papilla?

Answer 32

Later than

Question 33

Three types of tissues of dental sac in bell stage:

Answer 33

Cementum Periodontal ligament Alveolar process

Question 34

Apposition stage is also know as ...

Answer 34

secretory stage

Question 35

What occurs during the apposition stage

Answer 35

Enamel, dentin, and cementum are secreted in successive layers

Question 36

What happens in the maturation stage

Answer 36

stage is reached when matrices of hard dental tissue fully mineralize to their correct levels

Question 37

How does tooth development occur

Answer 37

Begins in crown and proceeds to the root

Question 38

What are preameloblasts

Answer 38

IEE cells that grow columnar and elongate and differentiate

Question 39

What is repolarization

Answer 39

moving of nucleus away from basement membrane

Question 40

What cells undergo cellular repolarization in preameloblast formation

Answer 40

IEE

Question 41

What does IEE induce what cells to become what?

Answer 41

Induces dental papilla cells to differentiate into dentin-forming cells (odontoblasts)

Question 42

What does IEE themselves differentiate into?

Answer 42

Ameloblasts (cells that secrete enamel)

Question 43

Preameloblasts induce outer dental papilla cells to become what?

Answer 43

Odontoblasts

Question 44

Dentinogenesis

Answer 44

Lays down dentin matrix (predentin)

Question 45

When preameloblasts come into contact with the new predentin what occurs

Answer 45

preameloblasts differentiate into ameloblasts

Question 46

What triggers enamel formation

Answer 46

Dentin formation

Question 47

What is amelogenesis

Answer 47

Growth of enamel matrix

Question 48

What is the enamel matrix secreted from

Answer 48

Tomes Process

Question 49

What is the tomes process

Answer 49

angled distal part of ameloblast

Question 50

What is an odontoblastic process

Answer 50

Cellular extension in length of predentin

Question 51

What are odontoblastic processes contained in

Answer 51

Dentinal tubule

Question 52

What ultimately happens to cell bodies of odontoblasts

Answer 52

Remain in adjoining pulp attached by odontoblastic processes

Question 53

What ultimately happens to ameloblasts

Answer 53

lost after tooth eruption