Primary Tooth Morphology Flashcards
(75 cards)
1
Q
4 examples of early problems
A
- gingival cysts (Epstein’s Pearls/Bohns Nodules)
- congenital epulis
- natal or neonatal teeth
- eruption cyts
2
Q
what are Gingival Cysts (Epstein’s Pearls/Bohns Nodules)?
A
name depends on location in mouth
- White lump on gum
- No teeth – very young
- Keratin build up
- No treatment as will naturally resolve
3
Q
what is congenital epulis?
A
- large bulbous swelling
- Can interfere with feeding
- Shrink as child grows
- Sometimes need removed
- Nothing untoward - not cancer, cant spread
4
Q
what are natal or neonatal teeth?
A
- tooth been in ectopic superficial position
- Erupt early
- Poor root support - can be mobile
- Interfere with feeding smooth them done
- May need extracted if too mobile
- Usually just monitor
- Can look hypominerlaised as not complete prior to eruption
i. e. lower central primary incisor
5
Q
what are eruption cysts?
A
- Blue swelling
- Over erupting primary teeth
- Blood has got into follicle space
- Can be left and resolve as tooth erupts
6
Q
how are the quadrants numbered in FDI notation for primary teeth?
A
5, 6, 7, 8 instead of 1, 2, 3, 4
7
Q
how are teeth numbered in FDI notation in primary teetH?
A
1, 2, 3, 4, 5
or A, B, C, D, E but never mix numbers and letters
8
Q
when do teeth start to form?
A
week 5 of intra-uterine life
9
Q
when does hard tissue of teeth begin to form?
A
week 13 of intra-uterine life
tooth germ can be seen on 20 week scan
10
Q
primary maxillary central incisor calcification timeline
A
- Start cal. 13-16 weeks i.u.l
- Crown complete 1.5 months after birth
- Eruption 8-12 months
- Root Complete 33 months
11
Q
primary maxillary second molar calcification dates
A
- Hard tissue formation 16-23 weeks i.u.l
- Crown formation complete at 11 months after birth
- Eruption between 25-33 months
- Complete root formation 47 months
12
Q
what can lead to enamel defects in babies?
A
systemic disturbances during calcification
13
Q
what are the 2 main causes systemic disturbances during calcification of enamel in babies?
A
- difficult pregnancy for the mother
- complications at birth.
14
Q
calcuication levels of crowns at birth
A
- ½ of central incisors
- ¹/3 of lateral incisors
- Tip of primary canines
- ½ of first primary molars
- ¹/3 of second primary molars
- Tip of cusps of first permanent molars
15
Q
how much of the central incisor crown is calcified at birth?
A
1/2
16
Q
how much of the lateral incisor crown is calcified at birth/
A
1/3
17
Q
how much of the primary canines crown is calcified at birth?
A
tip
18
Q
how much of the first primary molar crown is calcified at birth?
A
1/2
19
Q
how much of the second primary molar crowns is calcified at birth?
A
1/3
20
Q
how much of the permanent molar crowns are calcified at birth
A
tips
21
Q
what is needed for tooth eruption to occur?
A
force must be generated to propel the tooth through the bone and gingival tissue for eruption to occur
and in permanent dentition the primary tooth root must also be resorbed
22
Q
possible tooth eruption theories
A
- Cellular proliferation at the apex of the tooth
- Localized change in blood pressure/hydrostatic pressure
- Metabolic activity within the PDL
- Resorption of the overlying hard tissue
Likely to be combination of them all - unknown currently
23
Q
what causes resorption of the overlying hard tissue (bone)?
A
enzymes in the dental follicle
- Remodelling of bone or primary tooth tissue is essential to the process of tooth eruption
24
Q
how can the dental follicle best be seen?
A
as a dark halo around the unerupted tooth on radiographs
25
what happens when the dental follicle is activated?
initiate osteoclastic activity in the alveolar bone ahead of the tooth and clear a path for tooth eruption
• Don’t know what signals osteoclasts to go through bone and tooth eruption
• Leaves a trail
Once the crestal bone has been breached the follicle is likely to play a lesser role
• Just gingival tissue
26
what must occur at the base of the crypt during eruption?
bone growth as tooth pushes into mouth
Osteoclastic activity in front of tooth and bone deposition below tooth
27
when does the eruption process stop?
when the tooth comes into contact with something
- usually the tooth of the opposing arch
so continues throughout life to compensate for vertical growth of the jaws and tooth wear
- prevent anterior overbite
28
what is general role for lower and upper eruption times?
lower before uppers
| except the lateral incisors
29
what us the general eruption sequence?
```
A B D C E
central incisor,
lateral incisor,
first primary molar,
canine,
second primary molar
```
30
what is the first primary tooth to erupt? and when?
lower central incisor
| 4-6 months
31
what is the second wave of primary teeth to erupt? and when?
lower and then upper laterals
| 7-16 months
32
what is the third wave primary teeth to erupt? and when?
lower and then upper first molars
| 13-19 months
33
what is the fourth wave primary teeth to erupt? and when?
lower than upper canines
| 16-22 months
34
what is the fifth wave of primary teeth to erupt? and when
lower than upper second molars
| 15-33 months
35
how do teeth of the same series erupt in respect to each other?
teeth of the same series tend to erupt within 3 month of their contra lateral tooth
36
when is the primary dentition complete by?
2 and a half to 3 years
37
4 differences between primary and permanent teeth crowns
- The primary incisors are smaller in both their crown and root proportions.
- The primary molars are wider mesiodistally than the permanent premolars which take their place.
- Primary molars crowns are more bulbous.
- The primary teeth are usually whiter in colour. (Enamel structure is slightly different)
38
feature of upper and lower 1st primary molar
they have a prominent mesiobuccal tubercle
- succeeding permanent premolars do not have tubercles
39
feature of upper second primary molars
have a transverse ridge
| - when doing cavity preparation cannot break this ridge
40
feature of lower second primary molar
has 3 buccal cusps
| - like first permanent molar
41
3 differences between primary and permanent roots
- The roots of the primary teeth tend to be narrower when compared with their permanent counterparts.
- The roots of the primary molars are longer and more slender than the roots of the permanent molars.
- roots tend also to flare apically to allow room in between for the developing permanent tooth crowns.
42
2 differences between the pulp in primary and permanent teeth
- The pulp chambers of the primary teeth are relatively large in proportion to the crowns that surround them.
- The pulp horns of primary teeth extend high occlusally,
- placing them closer to the enamel than the pulp horns of permanent teeth; hence pulpal exposure on cavity preparation is more likely.
primary root canals tend to be ribbon shaped, with multiple interconnecting accessory canals
43
why is more care needed when carrying out restoration on primary teeth?
burs tend to be 2-3mm in length
- can easily breach pulp in primary teeth as thinner enamel and dentine, with a larger pulp chamber
decay is also more rapid as less enamel to penetrate
44
what is the shape of primary root canals?
ribbon shaped, with multiple interconnecting accessory canals
- clinically impossible to clean
- endodotics hard
45
2 hard tissue differences between primary and permanent teeth
- The thickness of the coronal dentine is much thinner than in permanent teeth.
- The enamel of the primary teeth is relatively thin and has a consistent depth.
- Unlike permanent
- In primary cusps and fissures are similar enamel depth
46
why is some anterior spacing desired in primary dentition?
so no crowding in permanent dentition
47
arthropoid or primate spacing
- Spacing mesial to upper deciduous canine
| - Spacing distal (and slightly mesial) to lower deciduous canine
48
leewat space
- extra mesio-distal space occupied by the primary molars which are wider than the premolars which will replace them
- Usually equates to 1.5mm per side on the upper arch and 2.5mm per side in the lower arch
49
how does the face grow?
downwards and forwards
| impact on occlusion
50
when does the mixed dentition stage occur?
when the first permanent tooth erupts until exfoliation of the last primary tooth
usually between 6 and 11 years
- but variations
- typically lasts 5 years
51
upper arch permanent teeth eruption sequence
1st permanent molars and then front to back except canines (premolars before them)
6, 1, 2, 4, 5, 3, 7, 8
52
lower arch permanent teeth eruption sequence
1st permanent molars and then front to back
6, 1, 2, 3, 4, 5, 7, 8
53
which permanent teeth arch erupts first?
lowers before uppers
except second premolars
54
crowding in the upper permanent arch leads to....
exclusion of the upper canine
55
crowding in the lower permanent arch leads to...
lack of space for second premolar
56
path of tooth eruption for permanent dentiton
- proclined permanent incisors lead to an increased A-P arch length as deciduous incisors were upright
- permanent incisors develop more palatal to primary incisors
- risk of trauma to the permanent teeth if primary incisors are displaced towards the developing tooth.
57
what is the "ugly duckling" phase? (physiological spacing)
Transient spacing of the upper 1’s may occur due to the close proximity of their roots to the erupting 2’s and 3’s
- Push on root and splay it out
- Until canine pushes its way down and closes
Physiological spacing
- changes as teeth come through
58
how long does it take for complete root formation for permanent teeth?
from eruption it takes around 3 years for permanent tooth root to complete apexogenesis
whereas primary roots was just 1.5 years
59
how many roots does a 65?
3 (one palatal and 2 buccal)
palatal root can be fused to buccal root
60
what is the occlusal surface of 65?
large transverse ridge
bulbous buccal cusp
2 fissure patterns
61
how many cusps does the 75 have?
2 lingual
| 3 buccal
62
which buccal cusp is largest on the 75?
mesial
63
which buccal cusps is the smallest on the 75?
smallest distal - round corner
64
how many roots does the 75 have?
2 roots
splayed due to permanent tooth
65
what can 61 root be like?
can have a distal bend
66
what can 61 crown be like?
mesial edge of crown is straighter
67
what is a difference in primary and permanent incisor?
more bulbous
68
what is the difference in upper and lower incisors?
lowers more slimmer mesio-distally
69
edges of 63 tend to be.....
mesial tends to be straighter
distal flares after ACJ
70
special feature of 64
tubrecle
can be very prominent (like a cusp)
71
occlusal surface of 64
- square shaped crown
- S/C shaped fissure
- tubercle
72
how many roots does upper first molar have? 64
2 roots - one buccal and one palatal
73
84 occlusal surface
- more retangular
- S shaped fissure
- mesiobuccal fissure
don't look like premolars that replace them
74
how many roots does lower 1st molars have?
2
| one can be seem fused
75
how many roots does the lower 2nd molar have?
3 roots
