Tooth development

Question 1

What are developmental phases of tooth development?

Answer 1

1) Initiation- development of tooth site along dental lamina
2) Morphogenesis- rise to tooth shape
3) Histogenesis - differentiation of cells

Question 2

What do ameloblasts and odontoblasts give rise to?

Answer 2

Mineralised tissue

non-mineralised tissue

Question 3

What is Mineralised tissue?

Answer 3

Dentine
ENAMEL
Cementum

Question 4

What is Non-mineralised tissue?

Answer 4

Pulp

Periodontal tissues

Question 5

What are the Stages of Tooth development?

Answer 5

1) Primary epithelial band at 6 weeks
2) Dental lamina formation at 7 weeks
3) Bud stage
4) Cap stage by 11th week
5) Bell stage by 14th week
6) mineralised tissue forms at 18th week
7) Hertwig’s root sheath and root formation
8) Alveolar bone and periodontal tissue formation

Question 6

What does embryonic oral epithelium have?

Answer 6

Superficial and Basal layer

Question 7

What occurs in the basal layer?

Answer 7

Where cells grow

Question 8

What is the Adult Oral mucosa have?

Answer 8

Superficial Layer
Intermediate layer
Basal layer

Question 9

What are superficial layer cells?

Answer 9

Large and flattened

Question 10

What are intermediate layer cells?

Answer 10

start to enlarge and flatten

Question 11

What are basal layer cells?

Answer 11

Tall columnar, actively reproducing

Question 12

Where do basal cells move towards overtime?

Answer 12

Superficial layer

Question 13

What occurs in Primary epithelial band of intra uterine life?

Answer 13

Multiplication of basal and superficial layer cells to increase tissue thickness

Question 14

What creates primary epithelial band?

Answer 14

cell signalling and gene expression within cells

Question 15

How is dental lamina formed at 7 weeks?

Answer 15

Selective Multiplication of basal layer cells only

Question 16

What happens in early bud stage?

Answer 16

1) ovoid epithelium condensation

2) No Morpho/Histodifferentiation

Question 17

What surrounds Ovoid epitheloum condensation?

Answer 17

Mesenchyme

Question 18

What happens at Cap Stage by 11th week?

Answer 18

1) Histodifferentiation occurs
- Stellate reticulum
- Outer enamel epithelium
- Inner enamel epithelium

Question 19

In Cap stage what are the basal cells continuous with?

Answer 19

Outer and Inner enamel epithelium

Question 20

What is stellate reticulum?

Answer 20

sic star shape- nutrient role for cells of Inner/outer enamel epithelium

Question 21

What happens at Bell stage at 14th week?

Answer 21

1) Successional lamina form
2) Morpho differentiation
3) Histodifferentiation -IEE become tall columnar cells

Question 22

What develops from the successional lamina?

Answer 22

Permanent incisor, canine, pre molar after deciduous tooth

Question 23

Where do permanent molars develop from?

Answer 23

Dental lamina since no deciduous teeth replaced

Question 24

What is visible in Bell stage?

Answer 24

OEE is cervical loop- where root cementum grows from

Question 25

What happens in Hertwig’s Root sheath and root formation?

Answer 25

Cervical loop becomes sheath

Question 26

What happens at Sheath?

Answer 26

Root dentine and cementum formed

Question 27

What is part of bell stage?

Answer 27

Dental sac and dental lamina form

Question 28

What are both dental sac and Papilla composed of ?

Answer 28

Mesodermal/Mesenchymal cells

Question 29

What do dental papilla cells differentiate into?

Answer 29

Pulp cells and odontoblast layer so pulp and dentine made

Question 30

What is dental sac composed of?

Answer 30

layers of flattened cells

Question 31

What are created from cells in dental sac?

Answer 31

Cementum
PDL
Some alveolar bone

Question 32

When are stellate reticulum no longer present?

Answer 32

once dental sac formed

Question 33

What happens in Dental tissue formation and late bell stage in 18th week?

Answer 33

Morphodifferentiation- INCISOR SHAPE
Histodifferentiation- AMELOBLAST and ODONTOBLAST develops
Alveolar bone deposited

Question 34

What is amelogenesis?

Answer 34

Enamel formation

Question 35

What are amelogenesis stages?

Answer 35

1/2) IEE diff. into columnar secretory cells with nucleus away from dentine

3) Ameloblast w/ initial matrix secreted
4a) Tomes process develops
4b) nucleus comes down and widens
5) Maturation phase- lose Tomes and shrink and enamel matrix removed
6) Post maturation- enamel shrink to form protective layer for enamel

Question 36

Where do Ameloblasts develop from?

Answer 36

Inner enamel epithelium

Question 37

What does ameloblast development induce?>

Answer 37

mesenchymal cells of dental papilla to produce ODONTOBLAST layer

Question 38

What does tomes process have?

Answer 38

Secretory vesicles that deposit enamel matrix protein and minerals to for HAP crystals

Question 39

When does Maturation phase occur?

Answer 39

When enamels full thickness reached

Question 40

What will ameloblasts contribute to form later on tooth eruption?

Answer 40

Junction epithelium

Question 41

What are enamel matrix proteins?

Answer 41

Tuftelin and Amelogenin

Question 42

What is Dentinogenesis ?

Answer 42

Formation of DENTINE

Question 43

What stimulated dentinogenesis?

Answer 43

Ameloblast differentiation stimulate mesodermal cell in dental papilla

Question 44

What are the stages to Dentinogenesis?

Answer 44

1) Pre-odontoblast & daughter cell proliferate
2) pre odont. develop into columnar secretory cells
3) Basal lamina of Ameloblast degrade
4) Dentine matrix strip deposited and mineralises

Question 45

What does degradal of ameloblast basal lamina cause?

Answer 45

allow cell signalling to odontoblast

Question 46

What does cell signalling to odontoblast cause?

Answer 46

• Nucleus down cell
• Odontoblastic process develop
• Dentine matrix starts to be laid down