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Flashcards in Primary Tooth Morphology Deck (27)
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1

What is the rule for order of eruption and what is the order of eruption

The lower teeth erupt before uppers with the exception of the lateral incisors
A,B,D,C,E
1,2,4,3,5

2

What is the first tooth to erupt and when does this occur

Lower central incisor at 4-6 months

3

When do each of the teeth in the primary dentition erupt

Central incisor - 4-6 months
Lateral incisor - 7-16 months
1st molar - 13-19 months
Canine - 16-22 months
2nd molar - 15-33 months

4

When is the primary dentition completed

By 2 and a half to 3 years of age

5

Contra lateral teeth usually erupt within what time period of each other

3 months

6

What is the difference between primary and permanent incisors

The primary incisors are smaller in both crown and root proportions

7

What is the difference between primary molars and permanent premolars

The primary molars are wider mesiodistally than the permanent premolars which take their place
Primary molar crowns are more bulbous

8

Describe the first primary molar

Doesn’t look like any other teeth
Has a prominent mesiobuccal tubercle

9

Describe the second primary molar

Have a transverse ridge running across the tooth - don’t want to cut through when doing preparations for the tooth
Looks like first permanent molar and has 3 buccal cusps

10

Compare the roots of primary teeth and permanent teeth

Roots of primary teeth tend to be narrower
Roots of primary molars are longer and more slender than the permanent molars
Primary molar roots tend to flare apical to allow room in between for the permanent tooth crowns

11

Compare the pulp of primary and permanent teeth

Pulp chambers of the primary teeth are relatively large in proportion to the crowns that surround them
Pulp horns of primary teeth extend high occlusally, placing them closer to the enamel than in permanent teeth - hence pulpal exposure on cavity preparation is more likely

12

Why do primary teeth become non-vital quickly if infected with caries

There’s not much distance for the bacteria to go before they invade the pulp

13

Compare the root canals of primary and permanent teeth

Primary tend to be ribbon shaped with multiple interconnecting and accessory canals and are clinically impossible to clean

14

Compare the enamel and dentine between primary and permanent teeth

The enamel of the primary teeth is relatively thin and has a consistent depth
The thickness of the coronal dentine is much thinner than in permanent teeth

15

Why is there spacing in the primary dentition

To prevent crowding in the permanent dentition

16

Where is the anthropoid or primary spacing found

Mesial to upper deciduous canine
Distal to lower deciduous canine

17

Define the leeway space

Extra mesio-distal space occupied by the primary molars which are wider than the premolars which will replace them

18

What is the leeway space

Usually 1.5mm per side on the upper arch and 2.5mm per side in the lower arch

19

How does the face grow as you grow

Downwards and forwards

20

When does the mixed dentition start and end

Begins from the time the first permanent tooth erupts until the exfoliation of the last primary tooth
Usually between 6 and 11 years

21

What is the eruption sequence of permanent teeth in the upper arch

First permanent molars and then front to back except canines
6,1,2,4,5,3,7,8

22

What is the eruption sequence of permanent teeth in the lower arch

First permanent molars and then front to back
6,1,2,3,4,5,7,8

23

What is the general rule for permanent teeth eruption

Lower teeth tend to erupt before upper teeth with the exception of second premolars

24

Draw the eruption date table for permanent teeth

7,8,11,10,10,6,12
1,2,3,4,5,6,7
1,2,3,4,5,6,7
6,7,9,10,10,6,12

25

Describe the ugly duckling phase

Transient spacing of the upper 1s due to the proximity of their roots the the erupting 2s and 3s
Central’s coming through and lateral is pressing on the root, flaring it out
As lateral comes down there is a canine pressing on the root there, flaring it out

26

How long does completion of root formation take

From the date of eruption it takes around 3 years for the permanent tooth root to complete apexogenesis and 1.5 years on average in the primary dentition

27

Describe the difference in size between the primary and permanent dentition

Primary dentition has a much shorter arch length