Primary Tooth Morphology & Chronology of Tooth Eruption

Question 1

what early problems can arise in babies/

Answer 1

• gingival cysts
• congenital epulis
• natal or neonatal teeth
• eruption cysts

Question 2

what are gingival cysts formed of? are they a cause for concern?

Answer 2

• formed of keratin

- not a problem

Question 3

what are teeth present at birth referred to?

Answer 3

natal teeth

Question 4

what are neonatal teeth?

Answer 4

teeth that erupt in the early days/weeks of life

Question 5

what teeth tend to be natal/neonatal?

Answer 5

lower primary central incisors

Question 6

when would natal/neonatal teeth require treatment?

Answer 6

• causing ulcers
• affecting mum when feeding
• very mobile teeth

Question 7

what is an eruption cyst?

Answer 7

• a cyst overlying where the developing tooth is about to erupt
• they look blue because it is filled with blood
• resolve on their own

Question 8

what is the upper right quadrant of the primary dentition in FDI notation?

Answer 8

5

Question 9

what is the upper left quadrant of the primary dentition in FDI notation?

Answer 9

6

Question 10

what is the lower right quadrant of the primary dentition in FDI notation?

Answer 10

8

Question 11

what is the lower left quadrant of the primary dentition in FDI notation?

Answer 11

7

Question 12

when do teeth start forming?

Answer 12

week 5 of intra-uterine life

Question 13

when does hard tissue formation start?

Answer 13

week 13 of intra-uterine life

Question 14

what is the eruption and root completion dates for a primary upper incisor?

Answer 14

• eruption 8-12 months

- root completion 33 months

Question 15

what are the eruption and root formation dates for a primary upper second molar?

Answer 15

• eruption = 25-33months

- root formation = 47 months

Question 16

defects in the primary dentition (which are not hereditary) are most likely due to what?

Answer 16

a difficult pregnancy for the mother or complications at birth

Question 17

what is a general rule in the order of eruption for the primary dentition?

Answer 17

the sequence tends to be

• central incisor
• lateral incisor
• first primary molar
• canine
• second primary molar

Question 18

do lower or upper teeth erupt first?

Answer 18

as a general rule, lower teeth erupt before upper (the exception is the LATERAL INCISORS)

Question 19

what is normally the first tooth to erupt?

Answer 19

the lower central incisor at around 4-6 months (quickly followed by the upper CI)

Question 20

what teeth tend to erupt at around 7-16 months?

Answer 20

the lateral incisors (52, 62, 72, 82)

Question 21

*roughly when does the first molar tend to erupt?

Answer 21

13 - 19 months

Question 22

what tooth tends to erupt at around 16-22 months?

Answer 22

the canines

Question 23

when do the 2nd molars erupt?

Answer 23

15-33 months

Question 24

when is primary dentition complete by?

Answer 24

approx. 2 and a half - 3 years

Question 25

how are primary incisors different to permanent incisors?

Answer 25

primary incisors are smaller in both their crown and root proportions

Question 26

how are primary molars different to permanent molars?

Answer 26

• primary molars are wider mesiodistally

- primary molar crowns are more bulbous

Question 27

what is an interesting anatomical feature of the first primary molars?

Answer 27

they have a prominent mesiobuccal tubercle

Question 28

what anatomical feature is found on upper second primary molars?

Answer 28

transfer ridge

Question 29

what anatomical features does the lower second primary molar have?

Answer 29

three buccal cusps

Question 30

how are the primary roots different to the permanent roots?

Answer 30

the roots of the primary teeth tend to be narrower when compared to permanent counterparts

Question 31

what is interesting about the primary pulps?

Answer 31

the pulp chambers of the primary teeth are relatively LARGE in proportion to the crowns that surround them

Question 32

what is interesting about the pulp horns in the primary dentition/

Answer 32

the pulp horns of primary teeth extend high occlusally (placing them closer to enamel)

Question 33

describe the root canals of primary teeth:

Answer 33

tend to be ribbon shaped with multiple interconnecting and accessory canals

Question 34

when primary teeth are in occlusion, what is typically seen?

Answer 34

anterior spacing (which is desirable)

Question 35

why is primary spacing desirable?

Answer 35

to avoid crowding in the permanent dentition

Question 36

what is the mixed dentition stage?

Answer 36

it begins from the time the first permanent tooth erupts, until the exfoliation of the last primary tooth

Question 37

when does the mixed dentition stage normally occur?

Answer 37

6 - 11 years