Tooth Development: Putting it all together

Question 1

What teeth would you expect to see in an 8 yr old?

Answer 1

Permanent first molars and incisors; primary canines and molars

Question 2

What type of radiographs would be needed for an 8 yr old new patient that is disastisfied with teeth?

Answer 2

Posterior bitewing w panoramic

Question 3

Do the crowns or roots develop first?

Answer 3

Crown

Question 4

What are the 5 stages of crown formation?

Answer 4

Initiation Stage
Bud Stage
Cap 
Bell
Enamel, dentin, and pulp formation

Question 5

corresponds to the dental arches and gives rise to dental lamina and vestibular lamina

Answer 5

Primary epithelial band

Question 6

_____ is expressed in the epithelium where the tooth bud would form

Answer 6

Shh

Question 7

_____is expressed in the mesenchyme where the tooth bud would form

Answer 7

Pax9

Question 8

_____ formation is an epithelial thickening important in the initiation of tooth development

Answer 8

Placode

Question 9

In initiation of tooth development, does the mesenchyme grow into the epithelia or does the epithelia grow into mesenchyme?

Answer 9

Epithelia outgrowth into mesenchyme

Question 10

Initial odontogenic potential lies in the epithelia or mesenchyme?

Answer 10

Epithelia

Question 11

The ________ induces the oral ectoderm to become to the dental lamina

Answer 11

Neural crest mesenchyme

Question 12

____ stage of tooth development:

• epithelial cells show no major changes
• Shh, Lef-1, and Eda-Edar involved in placode formation
• Mesenchyme beneath starts to condense by the factors secreted by the epithelium
• Cross-talk between the epithelium and the mesenchyme
• Odontogenic potential in the epithelium

Answer 12

Bud stage

Question 13

____ stage of tooth development:

• epithelium proliferates; mesenchyme continue to condense
• tooth germs present

Answer 13

Cap Stage

Question 14

Bud to cap stage transition is regulated by what 2 things?

Answer 14

Signaling molecules and transcription factors

Question 15

_____ is a tooth germ in the cap stage forming the enamel of the tooth

Answer 15

Enamel organ

Question 16

_____ is a tooth germ in the cap stage forming the denitn and pulp

Answer 16

Dental papilla

Question 17

Supporting structures (cementum/ periodontium/ alveolar bone proper) all come from _______

Answer 17

Dental follicle/sac

Question 18

____ is a key signaling centers that consists of non-dividing cells determines cusp formation;

Answer 18

Enamel knot

Question 19

Cells in enamel organ synthesize ______ in to the ECM; hydrophilic and pull water in to enamel organ

Answer 19

Glycosaminoglycans

Question 20

Enamel organ epithelial are separated into what 2 categories?

Answer 20

Inner and Outer enamel eptihelium

Question 21

____ stage of tooth development:

• under surface of the epithelium deepens and resemble a bell
• stratum intermedium formation
• crown attains full size and shape

Answer 21

Bell stage

Question 22

The junction of the inner enamel epithelium and outer enamel epithelium is called the _____: plays important roll in determining roots of teeth

Answer 22

Cervical loop

Question 23

____ stage of tooth development: (late)

• dental lamina breaks and separates the tooth from oral epithelium
• IEE completes folding forming the future crown pattern
• Folding is due to differential rates of mitotic division in IEE
• Under influence of IEE mesenchymal cells differentiate into odontoblasts that makes dentin
• IEE differentiate into ameloblasts and make enamel
• Site at which IEE differentiates determines future cusp formation

Answer 23

Late bell stage

Question 24

Does dentin or enamel form first?

Answer 24

Dentin

Question 25

Dentin forms from the ______

Answer 25

mesenchmye

Question 26

Permanent dentition forms _____ to the deciduous dentition

Answer 26

Lingual

Question 27

IEE and OEE from the cervical loop proliferate downward to form double layered structure called ______

Answer 27

Hertwig’s epithelial root sheath

Question 28

_____ are formed by:

• Fragmentation of Hertwig’s epithelial root sheath
• Differentiation of cementoblasts from Hertwig’s epithelial root sheath or dental follicle cells
• can be cellular or acellular

Answer 28

Cementum

Question 29

Remnants of Hertwig’s epithelial root sheath are called _____

Answer 29

Epithelial rests of Malassez

Question 30

Enamel formation is called ____

Answer 30

Amelogenesis

Question 31

What are the 7 stages of amelogenesis?

Answer 31

1. Morphogenic Stage
2. Histodifferentitation Stage
3. Initial secretory stage (no Tome’s process)
4. Secretory stage (Tome’s process)
5. Ruffle ended ameloblast of the maturative stage
6. Smooth ended ameloblast of the maturative stage
7. Protective stage

Question 32

___ stage of ameloblasts:

• intense synthetic and secretory activity
• forms enamel rod and inter-rod
• secrete granules on the newly formed mantle dentin
• proteins
• proteases

Answer 32

Secretory stage

Question 33

What are the 3 secretory proteins secreted in secretory stage of ameloblasts?

Answer 33

Amelogenin
Ameloblastin
Enamelin

Question 34

What are the 2 secretory proteases secreted in secretory stage of ameloblasts?

Answer 34

Enamelysin (MMP20)

Kallkrien

Question 35

____ dentin: first layer of dentin formed by the newly differentiated odontoblasts, hypomineralized, and only in the crown of the tooth

Answer 35

Mantle dentin

Question 36

____ dentin: formed during tooth development (4um/day)

Answer 36

Primary dentin

Question 37

____ dentin: formed after tooth eruption

Answer 37

Secondary dentin

Question 38

____ dentin: produced in response to injury to protect the pulp

Answer 38

Tertiary dentin