EXAM I Development of Primary Teeth

Question 1

tooth development can be seen as early as ___

Answer 1

the 6th week of embryonic life

Question 2

what will happen if a child is missing a tooth bud?

Answer 2

they will be missing both the primary and permanent teeth

Question 3

if a child is missing a tooth bud, it is the result of ___

Answer 3

lack of initiation or arrest in the proliferation of cells during the bud stage (initiation)

Question 4

what are supernumerary teeth the result of?

Answer 4

• continuing budding of the enamel organ in the bud stage (initiation)
• or cells become more differentiated and detach from the enamel organ, producing enamel and dentin in the cap stage (proliferation)

Question 5

if two primary teeth are fused, what is the likely outcome for the permanent counterparts?

Answer 5

one of the permanent teeth will be missing

Question 6

what are odontomas the result of?

Answer 6

cells become more differentiated or detached from the enamel organ, producing enamel and dentin in the cap stage (proliferation)

*this can also result in supernumerary teeth

Question 7

why do you want to extract a primary tooth if it has an odontoma associated with it?

Answer 7

because it can affect the eruption of the permanent tooth

Question 8

what is an epithelial cyst the result of?

Answer 8

during the cap stage (proliferation), cells may assume a secretory function, resulting in an epithelial cyst

Question 9

odontomas, supernumerary teeth, and epithelial cysts can all occur during the cap stage (proliferation). what determines the defect?

Answer 9

the degree of differentiation

Question 10

what happens in the bell stage (histo/morphodifferentiation)?

Answer 10

cells differentiate

• dental papilla = odontoblasts
• inner enamel epithelium = ameloblasts

Question 11

disturbances in the bell stage (histo/morphodifferentiation) affect ___

Answer 11

forms and size of teeth

ex. peg laterals, macrodontia, microdontia

Question 12

___ is the result of odontoblast disturbance during the bell stage

Answer 12

odontogenesis imperfecta

Question 13

___ is the result of ameloblast disturbance during the bell stage

Answer 13

amelogenesis imperfecta

Question 14

if ameloblasts are injured and cause a disturbance in appositional growth, what can result?

Answer 14

enamel hypoplasia

Question 15

what is interglobular dentin the result of?

Answer 15

disturbance in calcification, resulting in the lack of fusion of calcospherites

Question 16

at how many weeks in utero do primary central incisors begin to calcify?

Answer 16

14 (typically maxillary before mandibular)

Question 17

at how many weeks in utero do primary lateral incisors begin to calcify?

Answer 17

16

Question 18

at how many weeks in utero do primary canines begin to calcify?

Answer 18

17

Question 19

at how many weeks in utero do primary maxillary first molars begin to calcify?

Answer 19

15.5

Question 20

at how many weeks in utero do primary maxillary second molars begin to calcify?

Answer 20

19

Question 21

at how many weeks in utero do primary mandibular first molars begin to calcify?

Answer 21

15.5

Question 22

at how many weeks in utero do primary mandibular second molars begin to calcify?

Answer 22

18

Question 23

when does calcification of first permanent molars begin?

Answer 23

28 weeks in utero

Question 24

the primary maxillary second molar is similar to which permanent tooth?

Answer 24

maxillary first molar

Question 25

the primary mandibular second molar is similar to which permanent tooth?

Answer 25

mandibular 1st molar

Question 26

which primary tooth does not resemble any permanent tooth?

Answer 26

the mandibular first molar

Question 27

do primary crowns have a larger or smaller crown:root ratio than permanent crowns?

Answer 27

smaller

Question 28

describe the enamel and dentin of primary teeth compared to permanent teeth

Answer 28

both are thinner than permanent teeth (about 1/2 as thick)

Question 29

are primary or permanent teeth more cervically constricted?

Answer 29

primary

Question 30

on the primary maxillary first molar, which cusp is the largest and sharpest?

Answer 30

ML

Question 31

which primary tooth has a prominent cingulum?

Answer 31

maxillary central incisor

Question 32

describe the root of the primary maxillary canine

Answer 32

• it is more than 2x the cervical-incisal length of the crown
• distally inclined at the apical 1/3

Question 33

which primary root is not like any other?

Answer 33

mandibular first molar, mesial root when viewed from the mesial

Question 34

why do primary molar roots have more flare than permanent roots?

Answer 34

to accommodate the developing permanent teeth

Question 35

how do primary molar roots compare to roots of permanent molars?

Answer 35

they are relatively longer and more slender

Question 36

describe the pulps of primary teeth relative to permanent teeth

Answer 36

• larger pulps
• higher pulp horns
  
  • M higher than D
• pulp horns are closer to the DEJ
• pulp horn under each cusp
• shallow pulp chamber

Question 37

describe the root canal system of primary teeth

Answer 37

tortuous and complex; ribbon-like

Question 38

is bonding of primary teeth easier or harder than permanent teeth?

Answer 38

harder - you need more mechanical retention

Question 39

what is primate space?

Answer 39

• interproximal space that is eventually filled by permanent teeth
• in the maxillary arch, it is present between the lateral incisor and canine
• in the mandibular arch, it is present between the canine and the first molar

Question 40

what is leeway space?

Answer 40

• the combined MD lengths of the primary canine, 1st, and 2nd molars
• the combined MD lengths of the permanent canine, 1st premolar, and 2nd premolar
• the leeway space is the difference between these two lengths
  
  • primary is more than permanent