Primary Tooth Morphology Flashcards
What are some early problems that can occur before/after eruption?
Gingival cysts (Epstein pearls/ Bohns Nodules)
Congenital Epulis
Natal/ Neonatal teeth
Eruption cysts
What do gingival cysts look like?
White formed on the gingiva from keratin
Translate the FDI quadrants from permanent to primary teeth
1 = 5
2 = 6
3 = 7
4 = 8
When does hard tissue formation start?
Week 13/14
What can systemic disturbances during calcification cause?
Defects in enamel that was forming at that time
What must happen for a tooth to erupt?
A force must be generated to propel the tooth through the bone and gingival tissue (in case of permanent dentition, the primary tooth root must also be removed)
What are the possible theories behind tooth eruption?
what is the most likely
Cellular proliferation at the apex of the tooth
Localised change in blood pressure/hydrostatic pressure
Metabolic activity within the PDL
Resorption of the overlying hard tissue
What does resorption of the overlying hard tissue occur due to?
Enzymes in the dental follicle
How is the dental follicle seen on a radiograph?
A dark halo around the un erupted tooth
How does the follicle play an essential role in the tooth eruption?
Follicle initiates osteoclast activity in the alveolar bone ahead of the tooth and clears a path for tooth eruption. Once the crestal bone has been breached, the follicle is likely to play a lesser role
When does tooth eruption stop?
When the tooth comes into contact with something - usually the tooth of the opposing arch
Why does tooth eruption continue throughout life?
To compensate for vertical growth of the jaws and tooth wear
What arch erupts first and what is the exception?
primary
Usually mandible erupts first with the exception of the lateral incisors
What is the sequence of primary eruption? (In letters and names)
A, B, D, C, E
Central incisor, lateral incisor, first primary molar, canine, second primary molar
When do opposing teeth of the same series erupt in comparison to each other?
Within 3 months of each other
When is the primary dentition complete?
By 2 1/2 - 3 years of age
What dentition follows a more predictable pattern?
The permanent
What teeth are smaller in both their crown and root proportions?
Primary incisors
What are the primary molars wider mesiodistally than?
The permanent premolars which take their place
What are the crowns of primary molar more?
Bulbous
Which dentition is whiter?
Primary
What tooth is unlike any other tooth in the primary dentition and why?
Upper/lower 1st molar
It has a prominent mesiobuccal tubercle
What tooth has a transverse ridge in the primary dentition?
Upper 2nd molar
What tooth has three bucal cusps (similar to first permanent molar)?
Lower 2nd molar
What are the differences between primary and permanent teeth roots?
Primary teeth roots tend to be narrower and longer. They also flare apically to allow room in between for developing permanent crowns
What are the differences between primary and permanent tooth pulps?
Primary teeth have a large pulp chamber.
Primary pulp herons extend high occlusally, placing them closer to the enamel than the pulp horns of permanent teeth
What is more likely to happen in primary teeth during cavity preparation?
Pulpal exposure
What are the differences between primary and permanent root canals?
Primary tend to be ribbon shaped with multiple interconnecting and accessory canals (impossible to clean completely)
What is the differences between primary and permanent hard tissues?
Thickness of coronal dentine in primary is much thinner than permanent teeth
Enamel of primary teeth is relativity thin and has a consistent depth
What is desired in the primary occlusion?
Anterior spacing to avoid crowding in permanent dentition
What is the anthropoid/primate spacing found in primary occlusion?
In the upper arch - spacing mesial to upper canine
In the lower arch - spacing distal to lower canine
What is the leeway space?
Space occupied by the primary molars medio-dismally, for the premolars that will replace them
What is the measurement of the lee-way space?
1.5mm per side on upper arch
2.5mm per side on lower arch
What development affects the occlusion?
Facial growth
When does the mixed dentition stage begin and when does it end? (Plus what years?)
Begins at eruption of first permanent tooth
Ends at exfoliation of last primary tooth and eruption of permanent canine
Ages 6-11 years
What is the eruption sequence and ages of upper arch?
Permanent Teeth
6 years - 1st molar
7 years - central incisor
8 years - lateral incisor
10 years - 1st premolar and 2nd premolar
11 years - canine
12 years - 2nd molar
What is the eruption sequence and ages of lower arch?
Permanent Teeth
6 years - 1st molar and central incisor
7 years - lateral incisor
9 years - canine
10 years - 1st premolar and 2nd premolar
12 years - 2nd molar
What arch erupts first in the permanent dentition?
The lower with the exception of the second premolars
What does crowding in the upper arch usually lead to in permanent teeth?
Exclusion of the upper canine
What does crowding in the lower arch usually lead to in permanent teeth?
Lack of space for the second premolar
What is the difference in eruption of the canines in primary vs permanent teeth?
Primary canines are upright
Permanent canines are proclined leading to an increase in arch length
How do permanent incisors develop in comparison to primary?
Permanent develop palatal
What is the “ugly duckling phase”?
Transient spacing of upper 1’s may occur due to the close proximity of their roots to the erupting 2’s and 3’s
When does the root formation complete in both primary/permanent dentition?
Primary = 1.5 years
Permanent = 3 years
What are the differences in arch length of the primary and permanent teeth?
More length in the permanent
