Development of human dentition

Question 1

When does dental development begin?

Answer 1

6 weeks in utero

Question 2

When does the first primary tooth emerge?

Answer 2

6 months

Question 3

When does the first permanent tooth emerge?

Answer 3

6 years

Question 4

At what age have all crowns begun formation? When doe they finish formation?

Answer 4

5 months and 1 year old respectively

Question 5

By what age have all primary teeth emerged? Completed root formation?

Answer 5

2.5 years and 4 years respectively

Question 6

How do incisors in the primary dentition differ from the permanent?

Answer 6

More vertically positioned in the alveolus
More spaced
Greater overbite

Question 7

What is the relationship between the distal edges of the upper and lower molars in the primary dentition?

Answer 7

There is a flush terminal plane, even distal edges

Question 8

How does the mandible grow?

Answer 8

Retrudes then quickly grows forward

Question 9

How much leeway space is seen on the upper and lower?

Answer 9

1. 3-1.5mm per side on the top

2. 5-3.1mm per side on the bottom

Question 10

What happens to the circumference and arch length of the permanent dentition relative to the primary and why?

Answer 10

Decreases because there is a mesial drift of the 1st molar to occupy the leeway space

Question 11

The terminal plane uses what as a reference point?

Answer 11

The upper 2nd molar

Question 12

If the terminal plane has a distal step the bite is likely to become?

Answer 12

Full class 2 or end-to-end class 2

Question 13

A flush terminal plane is likely to become?

Answer 13

End-to-end class 2 or class 1

Question 14

A mesial step is likely to become?

Answer 14

Class 3 or 1

Question 15

How can you correct a single tooth crossbite?

Answer 15

Inclined plane

Question 16

The sac develops into?

Answer 16

The cementum, PDL, and alveolar bone

Question 17

The outer enamel epithelium becomes?

Answer 17

A protective barrier to the enamel organ

Question 18

The stellate reticulum becomes?

Answer 18

The enamel matrix

Question 19

The inner enamel epithelium becomes?

Answer 19

The ameloblasts which form the enamel matrix

Question 20

The outer cells of the papilla form?

Answer 20

The odontoblasts which form dentin

Question 21

The inner papilla becomes?

Answer 21

The pulp

Question 22

What is an early mesial shift?

Answer 22

When the mandibular 1st molar erupts around the age of 6 and closes the primate space resulting in class 1 occlusion

Question 23

When does occlusion come into alignment in those with a late mesial shift?

Answer 23

Around 11 years old after the primary molars are exfoliated. There are no primate spaces

Question 24

What is the general eruption sequence of the primary teeth?

Answer 24

ABDCE

CI, LI, 1st molar, canine, 2nd molar

Question 25

List the eruption sequence of the teeth, differentiate between upper and lower

Answer 25

A lower, A upper, B upper, B lower, D upper, D lower, C upper, C lower, E lower, E upper

Question 26

List when each primary tooth erupts

Answer 26

``` A lower- 6-8 months A upper- 7-10 months B upper- 8-11 months B lower- 9-13 months D upper- 12-15 months D lower- 12-16 months C upper- 16-19 months C lower- 17-20 months E lower- 20-26 months E upper- 25-28 months ```

Question 27

How much root formation is needed before a tooth will emerge?

Answer 27

1/2-2/3

Question 28

Describe the eruption sequence for the upper permanents?

Answer 28

6, 1, 2, 4, 5, 3, 7, 8

Question 29

For the lower permanents?

Answer 29

6, 1, 2, 3, 4, 5, 7, 8

Question 30

Describe the age of eruption for the upper teeth

Answer 30

``` 6 is between 6-7 1 between 7-8 2 between 8-10 4 and 5 are 10-12 3 is 11-13 7 is 11-13 8 is 17-20 ```

Question 31

Describe the age of eruption for the lower teeth

Answer 31

``` 6 and 1 are 6-7 2 is 7-8 3 is 8-10 4 is 10-12 5 and 7 are 11-13 8 is 17-20 ```