EXAM I Development of Primary Teeth Flashcards
tooth development can be seen as early as ___
the 6th week of embryonic life
what will happen if a child is missing a tooth bud?
they will be missing both the primary and permanent teeth
if a child is missing a tooth bud, it is the result of ___
lack of initiation or arrest in the proliferation of cells during the bud stage (initiation)
what are supernumerary teeth the result of?
- 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)
if two primary teeth are fused, what is the likely outcome for the permanent counterparts?
one of the permanent teeth will be missing
what are odontomas the result of?
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
why do you want to extract a primary tooth if it has an odontoma associated with it?
because it can affect the eruption of the permanent tooth
what is an epithelial cyst the result of?
during the cap stage (proliferation), cells may assume a secretory function, resulting in an epithelial cyst
odontomas, supernumerary teeth, and epithelial cysts can all occur during the cap stage (proliferation). what determines the defect?
the degree of differentiation
what happens in the bell stage (histo/morphodifferentiation)?
cells differentiate
- dental papilla = odontoblasts
- inner enamel epithelium = ameloblasts
disturbances in the bell stage (histo/morphodifferentiation) affect ___
forms and size of teeth
ex. peg laterals, macrodontia, microdontia
___ is the result of odontoblast disturbance during the bell stage
odontogenesis imperfecta
___ is the result of ameloblast disturbance during the bell stage
amelogenesis imperfecta
if ameloblasts are injured and cause a disturbance in appositional growth, what can result?
enamel hypoplasia
what is interglobular dentin the result of?
disturbance in calcification, resulting in the lack of fusion of calcospherites
at how many weeks in utero do primary central incisors begin to calcify?
14 (typically maxillary before mandibular)
at how many weeks in utero do primary lateral incisors begin to calcify?
16
at how many weeks in utero do primary canines begin to calcify?
17
at how many weeks in utero do primary maxillary first molars begin to calcify?
15.5
at how many weeks in utero do primary maxillary second molars begin to calcify?
19
at how many weeks in utero do primary mandibular first molars begin to calcify?
15.5
at how many weeks in utero do primary mandibular second molars begin to calcify?
18
when does calcification of first permanent molars begin?
28 weeks in utero
the primary maxillary second molar is similar to which permanent tooth?
maxillary first molar
the primary mandibular second molar is similar to which permanent tooth?
mandibular 1st molar
which primary tooth does not resemble any permanent tooth?
the mandibular first molar
do primary crowns have a larger or smaller crown:root ratio than permanent crowns?
smaller
describe the enamel and dentin of primary teeth compared to permanent teeth
both are thinner than permanent teeth (about 1/2 as thick)
are primary or permanent teeth more cervically constricted?
primary
on the primary maxillary first molar, which cusp is the largest and sharpest?
ML
which primary tooth has a prominent cingulum?
maxillary central incisor
describe the root of the primary maxillary canine
- it is more than 2x the cervical-incisal length of the crown
- distally inclined at the apical 1/3
which primary root is not like any other?
mandibular first molar, mesial root when viewed from the mesial
why do primary molar roots have more flare than permanent roots?
to accommodate the developing permanent teeth
how do primary molar roots compare to roots of permanent molars?
they are relatively longer and more slender
describe the pulps of primary teeth relative to permanent teeth
- larger pulps
- higher pulp horns
- M higher than D
- pulp horns are closer to the DEJ
- pulp horn under each cusp
- shallow pulp chamber
describe the root canal system of primary teeth
tortuous and complex; ribbon-like
is bonding of primary teeth easier or harder than permanent teeth?
harder - you need more mechanical retention
what is primate space?
- 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
what is leeway space?
- 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
