primary tooth morphology and chronology of tooth eruption Flashcards
1
Q
what are some early problems before the teeth erupt
A
- gingival cysts
- congenital epulis
- natal or neonatal tooth
- eruption cysts
2
Q
what is a gingival cyst
A
- white mark/lump
- type depends on location = Epstein Pearls, or Bohns nodules
3
Q
what is a congenital epulis
A
- can cause problems with feeding
- can shrink as child grows, may need removed
- not going to spread
- looks like a big balloon shape attached to gingiva
4
Q
what is a natal or neonatal tooth
A
- natal = there when born
- neonatal = erupts few days after birth
- usually primary lower incisors
- don’t have a lot of root so may be mobile = may need removed for safety
- can interfere with breastfeeding
- can look hyperplastic as mineralisation not started yet
5
Q
what are eruption cysts
A
- blue as blood from eruption of tooth goes into follicle spaces
- don’t need to do anything
6
Q
what is the tooth notation for primary teeth
A
- quadrants 1,2,3,4 are instead called 5,6,7,8 respectively
- teeth present are 1-5 or can be A,B,C,D,E
- so tooth 55 is the same as upper right E
- never use numbers are letters together
7
Q
when do teeth start to form
A
week 5 intra-uterine life (IUL)
8
Q
when does hard tissue formation of teeth start
A
week 13 IUL and can be detected on subsequent ultrasound scans
9
Q
at what week scan can you see tooth germs
A
20 week scan
10
Q
what are the dates for maxillary central incisor
A
- start calcification 13-16 weeks
- crown complete 1.5 months after birth
- eruption at 8-12 months after birth
- root complete at 33 months
11
Q
what are the dates for a maxillary second primary molar
A
- hard tissue formation 16-23 weeks IUL
- crown formation complete at 11 months after birth
- eruption between 25-33 months
- complete foot formation at 47 months
12
Q
what are some problems of calcification
A
- systemic disturbances during calcification can lead to defects in the enamel which was formed at that time
- defects in primary dentition (which are not hereditary) are most likely the result pf a difficult pregnancy for the mother or complications at birth
13
Q
what are the levels fo calcification of crowns at birth
A
- 1/2 of central incisors
- 1/3 of lateral incisors
- tip of primary canines
- 1/2 of 1st primary molars
- 1/3 of 2nd primary molars
- tip of cusps of 1st permanent molars
14
Q
is the exact eruption process known
A
no
- there are multiple theories but don’t know exact process
- likely to be multifactorial
15
Q
what must happen for tooth eruption
A
- a force must be generated to propel the tooth through bone an gingival tissue
- in permanent dentition, the primary tooth must also be removed in some cases
16
Q
when does a tooth stop erupting
A
- when it hits something
- keeps going throughout life but don’t know as you wear down your tooth
17
Q
what are the theories of eruption
A
- cellular proliferation at apex of the tooth
- localised change in blood pressure/hydrostatic pressure
- metabolic activity within PDL
- resorption of overlying hard tissue
18
Q
how does resorption of overlying hard tissue occur
A
- occurs due to enzymes in dental follicle
- dental follicle is best seen. on radiograph as a dark halo around the unerupted tooth
- remodelling of bone or primary tooth tissue is essential to process of tooth eruption
- animal models have shown that resorption is not necessary for eruption though however
19
Q
what role does dental follicle play in eruption
A
- shown to play essential role
- is activated to initiate osteoclastic activity in the alveolar bone ahead of the tooth and clear a path for tooth eruption
- once crystal bone has been breached, the follicle is likely to play a lesser role
20
Q
how does the tooth push into the mouth
A
- root elongation, PDL, local changes in vascular pressure are major factors
- although bone growth at base of the crypt is essential for eruption, it is possible that this is simply reactive to tooth movement
21
Q
how does eruption occur
A
- happens gradually
- stops when tooth come into contact with something else (opposing tooth)
- continues throughout life to compensate for vertical growth of the jaws and toot wear
22
Q
what are the ages of eruption for primary teeth
A
- upper central = 7 months
- upper lateral = 9 months
- upper canine = 18 months
- upper 1st primary molar = 14 months
- upper 2nd primary molar = 24 months
- lower central = 6 months
- lower lateral = 7 months
- lower canine = 16 months
- lower 1st primary molar = 12 months
- lower 2nd primary molar = 20 months
23
Q
what is the order of eruption
A
- as a general rule the lower teeth erupt before uppers with exception of lateral incisors
- sequence tends to be central incisor, lateral incisor, 1st primary molar, canine then 2nd primary molar
- ABDCE or 12435
24
Q
what is normally the first tooth to erupt
A
lower central at 4-6 months
- in FDI it is 71 or 81
25
what is the second tooth to erupt after centrals
- lateral incisors at 7-16 months
| - 52, 62, 72 ,82
26
what is the tooth to erupt after the lateral incisors
- 1st molars at 13-19 months
| - 54,64,74,84
27
what is the tooth to erupt after the 1st primary molar
- canine at 16-22 months
| - 52,63,73,83
28
what tooth erupts last
- 2nd primary molar at 15-33 months
| - 55, 65, 75 ,85
29
when do teeth usually erupt compared to their contralateral tooth
within 3 month
30
when is primary dentition normally complete by
2 1/3 - 3 years
31
which dentition is more predictable
permanent dentition
32
what are some differences between primary and permanent tooth crown
- primary incisors are smaller in both crown and root
- primary molars are wider mesiodistally than permanent premolars
- primary molar crowns more bulbous
- primary teeth usually more whiter (enamel is different)
33
what is the morphology of the 1st primary molar
- has prominent mesiobuccal tubercle (replacing premolars do not)
34
what is the morphology of the upper 2nd primary molar
- has a transverse ridge diving the occlusal surface
| - runs from disco-buccal cusp to messy-lingual
35
what is the morphology of the lower 2nd primary molar
- has 3 buccal cusps (like permanent first molar)
36
what are the differences between primary and permanent roots
- primary tend to have narrower roots
- primary are longer and more slender in primary molars compared to permanent and tend to flare apically to allow room for tooth crowns of permanent underneath
- root canals in primary tend to me more flat and thin with accessory canals
37
why can't primary teeth root canals not be cleaned well
- due to multiple accessory canals and because they are so flat and thin
- clinically impossible to clean completely
38
what are differences between primary and permanent pulps
- pulp chambers in primary teeth are relatively large compared to crowns surrounding them
- pulp horns of primary extend high occlusal, placing them closer to the enamel (pulpal exposure more likely in primary teeth when doing cavity prep)
39
what are the differences between primary and permanent hard tissue
- in primary thickness of coronal dentine is much thinner than permanent
- enamel of primary teeth is relatively thin and has a consistent depth
40
what are differences in occlusion between primary and permanent teeth
- some anterior spacing in primary is good as means less chance of crowding in permanent
- when face grows wit permanent dentition it affects occlusion (downward and forward growth of the facial portion of the skull
41
what is anthropoid or primate spacing
- spacing mesial to upper deciduous canine
| - spacing distal to lower deciduous canine
42
what is the leeway space
- extra messy-distal space occupied by the primary molars which are wider than the premolars replacing them
- usually equates to 1.5mm per side on upper arch and 2.5mm per side I the lower arch
43
when does mixed dentition stage begin and end
from the time the 1st permanent tooth erupts, until the exfoliation of the last primary tooth
44
what age is mixed dentition usually
between 6 and 11 years but it can vary
| - about 5 years
45
when is 1st permanent molar usually erupted
at age 6
46
at what age is the permanent canine usually erupted
age 11, although uppers may not be until 12/13
47
what is the eruption sequence of the permanent dentition typically
upper arch = 6, 1, 2, 4, 5, 3, 7, 8 (1st permanent molar first then front to back except canine)
lower arch = 6, 1, 2, 3, 4, 5, 7, 8 (1st permanent molar then front to back)
48
what is a general rule about eruption of permanent teeth
lower teeth tend to erupt before upper teeth with exception of second premolars
49
what are the eruption dates
```
upper = 1 age 7, 2 age 8, 3 age 11, 4 age 10, 5 age 10, 6 age 6, 7 age 12
lower = 1 age 6, 2 age 7, 3 age 9, 4 age 10, 5 age 10, 6 age 6, 7 age 12
```
50
what can crowding lead to in the upper arch
exclusion of the upper canine
51
what can crowding in the lower arch lead to
lack of space for second premolar
52
what leads to an increase in AP arch length
- deciduous teeth incisors having upright stance and replacing permanent incisors having a more proclaimed stance
53
what is the eruption path of incisors
- permanent incisors develop palatal to primary incisors
54
what is often termed the 'ugly duckling phase'
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
55
when does the root form
from date of eruption it takes around 3 years for the permanent root to complete to complete apexogenesis
- whereas in primary it only takes 1.5 years on average
56
does arch length increase a lot from primary to permanent dentition
yes - arch length increases a huge amount from primary to permanent dentition
