Primary Tooth Morphology Flashcards
describe gingival cysts
- found on the palate and gingiva
- these are developmental collections of keratin that can be ignored
- they seem concerning to parents and sometimes are misdiagnosed as erupting teeth but they will resolve by themselves
- no actual treatment, just reassure the parents and the child that it is nothing to be concerned about
describe congenital epulis
this is a growth in the mucosa of a newborn and can progress and interfere with feeding
if it interferes can be managed via surgery but otherwise it will be left to resolve on its own
describe neonatal teeth
these are teeth present at birth or those that develop soon after birth and they are very common
usually the primary incisors will develop ectopically when neonatal, they should not be removed unless they threaten the airway by wiggling around or if they are causing ulcerations
if there are issues with feeding because of them they can be smoothed down
due to erupting early they are not always fully formed
describe eruption cysts
the tooth develops in a follicle and blood can sometimes end up in the follicle which gives a blue hue
when the tooth erupts the cyst will resolve
describe the use of notation for primary teeth
the quadrants are called 5, 6, 7 and 8 and can be referred to as letters or numbers but never both at the same time
use FDI notation in the exam
is there more variation in primary or permanent dentition
primary
when should tooth calcification stop
a month and half after birth
what are some examples of systemic disturbances that can lead to enamel defects
infections and reduced oxygenation
when does tooth eruption stop
when the teeth contact something - this is usually the opposing arch gingiva or teeth
what are the differences between primary and permanent dentition
primary is smaller due to smaller jaws, both the roots and crowns are smaller
the primary molars are wider mesiodistally and more bulbous which is an important note for restorations
they are whiter in colour due to the enamel and dentine being thinner due to less space
identifying feature of upper first primary molar
prominent mesiobuccal tubercle
identifying feature of lower first primary molar
prominent mesiobuccal tubercle - not as prominent as the upper first primary molar
identifying feature of the upper right second molar
transverse ridge
explain the roots of primary teeth
narrower than permanent teeth
flat, and ribbon shaped
thin and flare apically
why do the roots of primary teeth flare apically
due to the permanent tooth germ growing in the middle of the root
describe the pulp chambers of the primary teeth
smaller than permanent, but in proportion to the size of the actual tooth they are large
the horns are closer to enamel than in permanent dentition so it is more likely that the pulp will be exposed
the canals are often ribbon shaped and have many accessory canals
primary enamel description
consistently thin around the tooth rather than varying in thickness like in the permanent dentition
is it good if there is little spacing between primary teeth
no
why is it difficult to completely clean out the root canal of primary teeth
they are flat and ribbon shaped when the end files are conical
in what direction does the face grow
Down and outward
when does mixed dentition last until
the final tooth exfoliates
what does exfoliate mean
the natural process of shedding the primary teeth
describe how the path of eruption between primary and permanent dentition differs
the angulation is different
primary are upright
permanent are inclined backward to increase the length of the arch
they develop palatal to the primary teeth
how can the age of a child be determined from their dental radiograph
whether the roots are formed or not
for permanent teeth, roots are formed at three years of age
for primary tech, roots are formed at 1.5 years
what are some early problems that can occur in the dentition of children
gingival cysts
congenital epulis
natal or neonatal teeth
eruption cysts
what are epsteins pearls an example of
gingival cysts
what are bohns nodules examples of
gingival cysts
how are the quadrants numbered in primary dentition
5 6
8 7
when do teeth start to form
week 5 of inter uterine life
when does hard tissue formation begin
week 13 of inter uterine life
when can teeth be detected on ultrasounds
after week 13 because this is when hard tissue formation begins
when does the maxillary central incisor begin to calcify
between weeks 13 and 16
when does the crown of the maxillary central incisor completely calcify
1.5 months after birth
in what month post birth will the maxillary central incisor erupt in a child
8-12 months
when does the root completely calcify for the maxillary central incisor in primary dentition
33 months
describe the chronology of the maxillary second primary molar
hard tissue formation at 16-23 weeks i.u.l
crown formation complete at 11 months after birth
eruption between 25-33 months after birth
complete root formation at 47 months
what can lead to defects in the enamel
systemic disturbances during calification
what are defects in primary dentition that are non hereditary most likely the result of
difficult pregnancy for the mother or complications at birth
how calcified are central incisors at birth
a half
how calcified are lateral incisors at birth
a third
how calcified are primary canines at birth
just the tip
how calcified are primary molars at birth
a half
how calcified are second primary molars at birth
a third
how calcified are cusps of permanent molars
the tips
what are some theories of how teeth erupt
- cellular proliferation at the apex of the tooth
- localised change in blood pressure
- metabolic activity in the periodontal ligament
- resorption of overlying hard tissue
describe the resorption of overlying hard tissue in teeth
- due to enzymes in the dental follicle
- the follicle is best seen on the radiograph as a dark halo around the unerupted tooth
- the remodelling of bone or primary tooth tissue is essential to the process of tooth eruption
- animal models have shown that resorption processes can be uncoupled from the eruption process meaning it is not necessary for the tooth to erupt to cause the bone to resorb
describe the role of the dental follicle in tooth eruption
the follicle plays an essential role in active tooth eruption
activated to initiate the osteoclastic activity in the alveolar bone ahead of the tooth and clear a path for tooth eruption
once the crystal bone has been breached the follicle plays a lesser role
does eruption ever end
- it stops when the tooth comes into contact with something
- however it will continue throughout life to compensate for the vertical growth of the jaws and tooth wear
- teeth have to constantly have something opposing them or they will continue to erupt
what is the order of eruption
a b d c e
central incisor
lateral incisor
first molar
second molar
canine
what is the general rule to primary tooth eruption and what is the exception to this rule
lower teeth erupt before the upper teeth
the lateral incisors are the exception, the upper will erupt before the lower
what is usually the first primary tooth to erupt
the lower central incisor - 4-6 months
FDI notation for lower central incisor
81 71
FDI notation for the primary lateral incisor
52, 62, 72 and 82
at what months for the primary lateral incisors erupt
7-16 months
FDI notation for the first molars
54, 64, 74, 84
at what month do the primary first molars erupt
13-19 months
FDI notation for the primary canines
53, 63, 73, 83
at what month do the primary canines erupt
16-22 months
FDI notation for primary second molars
55, 65, 75, 85
at what month do the primary second molars erupt
15-33 months
what is the normal period of time between the eruption of a tooth and their contralaterals
three months
at what age is primary dentition complete
2.5-3 years of age
identifying feature of lower right second primary molars
three buccal cusps like the permanent successor
describe the roots of primary molars
longer and more slender than the roots of permanent molars
flare apically to allow room in between for developing permanent tooth crowns
why is pulpal exposure on cavity preparation more likely in primary teeth than in permanent teeth
the pulp horns extend high occlusally, placing them closer to the enamel than the pulp horns of the permanent teeth
describe root canals on primary teeth
ribbon shaped with multiple interconnecting and accessory canals
difference between dentine in primary and permanent teeth
the thickness of coronal dentine is much thinner than in permanent teeth
difference between the enamel of permanent teeth and primary
the enamel of the primary teeth is thin and has a consistent depth
why is it desirable to have spacing in the primary dentition
so there is no crowding in the permanent dentition
describe the occlusion of primary canines
lowers space mesial to upper canines and uppers space distal to Lower canines
what is leeway space
extra mesiodistal space occupied by the primary molars which are wider than the premolars that replace them
equates to 1.5mm per side on the upper arch and 2.5mm per side in the lower arch
what is the mixed dentition stage
begins from the first permanent tooth eruption and ends at the exfoliation of the last primary tooth
usually between 6 and 11 years of age
eruption sequence of upper permanent teeth
6, 1, 2, 4, 5, 3, 7, 8
eruption sequence of lower permanent teeth
6, 1, 2, 3, 4, 5, 7, 8
age when upper permanent 1 erupt
7 years
age when permanent upper 2 erupts
8 years
age when upper permanent 3 erupts
11 years
age when upper permanent 4 erupts
10 years
age when upper permanent 5 erupts
10 years
age when upper permanent 6 erupts
6 years
age when upper permanent 7 erupts
12 years
age when lower permanent 1 erupts
6 years
age when lower permanent 2 erupts
7 years
age when lower permanent 3 erupts
9 years
age when lower permanent 4 erupts
10 years
age when lower permanent 5 erupts
10 years
age when lower permanent 6 erupts
6
age when lower permanent 7 erupts
12 years
what does crowding in the upper arch usually lead to
exclusion of the upper canine
what does crowding in the lower arch usually lead to
lack of space for the second premolar
what can lead to trauma risk when central incisors are erupting
if the primary are displaced toward the development permanent then there can be a trauma risk
what is the ugly duckling phase
this is transient spacing of the upper 1s that can occur due to the close proximity of their roots to the erupting 2s and 3s
how long from the date of eruption does it take for the permanent tooth root to complete apexogenesis
three years
what is apexogenesis
continuation of root development that leads to normal root length and apical closure
how many primary teeth are there
20
at what age does eruption begin for primary teeth
6 months
what are the primary teeth
two incisors, canine and two molars
at what age do the roots of primary dentition complete
3 years
which primary are the most unstable
the maxillary incisors and the second molars of both arches
eruption sequence for primary teeth
central, lateral, first molar, canine, second molar
loss sequence of primary teeth
incisors, first molars, canines and second molars
what is the high peak for caries attack in primary teeth
13 years of age
why is premature loss of primary teeth to be avoided
primary teeth have a role in mastication and in maintaining space for eruption of the permanent teeth
lack of space associated with premature loss is a significant factor in the development of malocclusion
describe the eruption the first permanent molar
otherwise known as the six year molar, arrives before any of the permanent teeth are lost and comes in immediately distal to the primary second molar
which primary tooth has a form unlike any of the permanent teeth
the deciduous mandibular first molar
how do the cervical ridges differ between deciduous and permanent teeth
the deciduous have more prominent cervical ridges and are narrower at their necks
how do the roots differ between deciduous and permanent teeth
they are more widely flared in the deciduous teeth
compare the primary anterior teeth to the permanent
- crowns are wider mesiodistally in comparison to the crown length compared to permanent teeth
- roots are narrower and longer. narrow roots with wide crowns presents an arrangement at the cervical third of crown and root that differs from the permanent anterior teeth
why are the roots of the primary molars longer and more slender and flare more
allows more room between the roots for the development of permanent tooth crowns
how do the cervical ridges of the primary molars differ
they are more pronounced buccally, especially in the first molars
differences between the primary and the permanent pulp chambers and canals
- crown width in all directions are large in comparison with the root trunks and crevices
- the enamel is thin and has consistent depth
- dentine thickness between pulp chambers and enamel is limited
- pulp horns are high and chambers are large
- primary roots are narrow and long in comparison to the crown width and length
- molar roots of primary teeth flare and thin out rapidly as the apices are approached
maxillary lateral incisor primary
primary maxillary canine
primary mandibular canine
mandibular lateral incisor
mandibular central incisor
describe the lingual aspect of the primary anterior teeth
well developed marginal ridge and highly developed cingulum
cingulum extends up toward the incised edge far enough to make a partial division of the concavity on the lingual surface below the incisal edge
describe the medial and distal aspects of the primary maxillary central incisor
curvature of the cervical line represents the cementoenaml junction and is distinct and curves toward the incisal ridge
the medial curvature is more pronounced than the distal curvature
which tooth is this describing: the mesial surface of the root will have a developmental groove or concavity whereas distally the surface is convex
primary maxillary central incisor
what is an important feature of the incisal edge of the maxillary central incisor
the measurement mesiodistally compared to the measurement labiolingually.
labial surface is much broader and smoother than the lingual surface and the lingual surface tapers toward the cingulum
tooth formation begins at which stage of embryonic life
week 5
what are the two stages of permanent tooth eruption
- incisor teeth and permanent first molars erupt
- other teeth in the buccal segments then follow
what does it mean if the upper lateral erupts before the upper central incisor
there is almost certainly something impeding the eruption of the central like a supernumerary tooth or a dilaceration of the upper central root
why are the permanent upper central incisors more proclined than their primary counterparts
to allow forward repositioning of the mandible when the first permanent molars erupt in a cusp to cusp relationship with their opponents
