Primary tooth morphology Flashcards
What are early problems that can affect children even before they are born
- gingival cysts
- congenital epulis
- natal or neonatal teeth
- eruption cysts
What are gingival cysts also known as
epstein’s pearls or bohns nodules
what do gingival cysts look like? Are they a problem?
small white ‘pearls’
What does a congenital epulis look like? What happens to them? Are they a problem?
a massive red bulge out of the mucosa.
will shrink as child grows or can be removed. Not dangerous
What problems can natal or neonatal teeth cause?
do they tend to be removed?
can be mobile and cause ulcers, not got as strong roots. Sometimes are taken out if a big interference but otherwise not.
What does an eruption cyst look like? What causes it? Is it a problem?
a blue blob on the mucosa, blood has got in there, no it will resolve
what is the notation of an upper right second primary molar?
What is really important about primary tooth notation
5,5
or
upper right E
never use numbers and letters together
When do teeth start to form?
week 5 of intrauterine life
When does hard tissue start to form
week 13 of iul
What are the calcification dates of the maxilary central incisor
start cal 13-16 weeks iul
crown complete 1.5 months after birth
eruption 8-12 months
root complete 33 months
(see welbury text page 12)
What is the chronology of the maxilary second primary molar
hard tissue formation, crown formation, eruption, complete root formation
hard tissue formation 16-23 weeks iul
crown formation complete at 11 months after birth
eruption between 25-33 months
complete root formation 47 months
How might the process of calcification cause defects in primary teeth
- systemic disturbances during calcification can lead to defects in the enamel which was forming at that time
- defects in the primary dentition (which are not hereditary) are most likely the result of a difficult pregnancy for the mother/ birth complications
How much of central incisors are calcified at birth
1/2
How much of lateral incisors are calcified at birth
1/3
How much of primary canines are calcified at birth
the tip
How much of first primary molars are calcified at birth
1/2
How much of second primary molars are calcified at birth
1/3
How much of permanent molars are calcified at birth
tip of cusps
what are the possible theories behind tooth eruption
- 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
why does resorption of the overlying hard tissue occur
due to enzymes in the dental follicle
what does the dental follicle look like on a radiograph?
a dark halo round the unerupted tooth
what process is essential for the process of tooth eruption
remodelling
however, it is not necessary for the tooth to erupt to cause resorption of bone
what role does the dental follicle play in tooth eruption
is activated to initiate osteoclastic activity in the alveolar bone ahead of the tooth and clear a path for tooth eruption
(once crestal bone has been breached the follicle is likely to play a lesser role)
how does eruption occur
- occur gradually
- stops when the tooth comes into contact with something-usually the tooth of the opposing arch
- continues throughout life to compensate for vertical growth of the jaws and tooth wear
what is the order of eruption (general rules)
lowers before uppers except lateral incisors
central incisor, lateral incisor, first primary molar, canine, second primary molar
ABDCE
12435
what is the eruption dates for the lower central incisor
4-6 months
what is the eruption dates for the lateral incisors
7-16months
what is the eruption dates for the 1st molars
13-19 months
what is the eruption dates for the canine
16-22 months
what is the eruption dates for the 2nd molar
15-33 months
teeth of the same series normally erupt between x of their contra lateral tooth
3 months
when is primary dentition normally complete by
2.5 - 3 years
what is more predictable - eruption of primary or permanent dentition
permanent dentition
how do the crowns of primary teeth differ from the crowns of permanent teeth
- the primary incisors are smaller in both their crown and root proportions
- the primary molar are wider mesiodistally than the permanent premolars which take there place
- primary molars crowns are more bulbous
- primary teeth are usually whiter
what is the defining feature of an upper 1st primary molar
prominent mesiobuccal tubercle
what is the defining feature of the lower 1st primary molar
prominent mesiobuccal tubercle
what is the defining feature of the upper 2nd primary molar
transverse ridge
what is the defining feature of the lower 2nd primary molars
three buccal cusps (like first permanent molar)
how do the roots differ between primary and permanent teeth
- primary teeth tend to have narrower roots
- primary molars have longer and more slender roots than permanent molars
- roots tend to flare apically to allow room in between for the developing permanent tooth crowns
how does the pulp differ between primary and secondary 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 of permanent teeth - hence pulpal exposure on cavity preparation is more likely
how do the root canals differ between primary and secondary teeth?
tend to be ribbon shaped with multiple interconnecting and accessory canals (clinically impossible to clean completely)
how does the hard tissue differ between primary and secondary 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
why do we want anterior spacing in the primary dentition
to prevent crowding in permanent dentition
what is anthropoid or primate spacing
spacing mesial to upper deciduous canine
spacing distal to lower deciduous canine
what is leeway space
extra mesio-distal space occupied by the primary molars which are wider than the premolars which will replace them
- 1.5mm per side on uppers
- 2.5mm per side in lowers
how does facial growth affect occlusion
downward and forward growth of the facial portion of the skull
when is the mixed dentition stage
from the eruption of the first permanent tooth to the exfoliation of the last primary tooth
ages 6-11 roughly
what is the eruption sequence of permanent teeth
uppers
1st permanent molars then front to back except canines
(61245378)
lowers
1st permanent molars then front to back
(61234578)
lowers before uppers except second premolars
lower teeth tend to erupt before upper teeth except x
second premolars
crowding in the upper arch usually leads to the exclusion of what tooth
upper canine
crowding in the lower arch usually leads to the exclusion of what tooth
second premolars
how do primary incisors occlude
upright
how do permanent incisors occlude
proclined
when is 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
how long after eruption does it take for the permanent tooth root to complete apexogenesis
3 years
how long after eruption does it take for the primary tooth root to complete apexogenesis
1.5 years
