The Development Of Occlusion Flashcards
What are some key points about the primary dentition?
Eruption times vary (+/- 6 months)
Calcification begins 4-6 months in utero
Root formation is complete 12-18 months after eruption
What is the sequence of eruption of primary teeth?
A-b-d-c-e
Which primary teeth erupt earlier in the maxilla?
B-c-d
What are some other facts about primary dentition eruption?
Girls erupt faster than boys
No significant left/right differences
What are the eruption times of the central (a) in the primary dentition?
Maxilla- 10 months
Mandible- 8 months
What are the eruption times of the lateral (b) in the primary dentition?
Maxilla- 11 months
Mandible- 13 months
What are the eruption times of the cuspid (c) in the primary dentition?
Maxilla- 19 months
Mandible- 20 months
What are the eruption times of the 1st molar (d) in the primary dentition?
Maxilla- 16 months
Mandible- 16 months
What are the eruption times of the 2nd molar (e) in the primary dentition?
Maxilla- 29 months
Mandible- 27 months
Eruption times in order of primary dentition
(A) mandible, (a) maxilla, (b) maxilla, (b) mandible, (d) maxilla, (d) mandible, (c) maxilla, (c) mandible, (e) mandible, (e) maxilla
What key stages have been reached by 2.5 years?
Primary dentition established
Primary incisors are more vertical than their permanent incisors
There may be primate spacing
What changes take place between 2.5-5.5 years?
Sometimes an increasing in spacing due to increase in arch width
Sometimes occlusal attrition leads to an edge-to-edge incisal relationship (mandible grows forward)
What things are important to check for in the primary dentition?
Spacing Crossbites Overjet Overbite Early loss- space loss Incisor trauma- secondary incisor dilaceration
If there is crowding in the primary dentition what is the predicted outcome in the permanent dentition?
Almost certain extractions will be needed
If there is no spacing in the primary dentition what is the predicted outcome in the permanent dentition?
Possible extractions needed
If there is fair spacing in the primary dentition what is the predicted outcome in the permanent dentition?
Mild to moderate crowding
If there is good spacing in the primary dentition what is the predicted outcome for the permanent dentition?
No or mild crowding
If there is excess spacing in the primary dentition what is the predicted outcome for the permanent dentition?
No crowding/excess spacing
At what age does the mixed dentition begin to form?
6 years old
What teeth usually emerge first in the permanent dentition?
Usually the permanent 1st molars o lower central incisors emerge first
What are some important things to check in the mixed dentition?
Ankylosis (fusion of the alveolar bone and cementum, can be associated with hypodontia)
Carious first molars (good OHI and diet practices- fluoride varnish)
Early loss of deciduous molars
Ectopic eruption of 1st molars/maxillary canines
Eruption failure
Missing teeth/extra teeth
What are some facts about carious first molars?
There is no good time to extract them
Caries prevention is better than cure
Space closure in the upper arch is usually good
Space closure in the lower arch is poor
Extraction of 1st molars doubles the treatment time and halves the prognosis
What is hypodontia?
The absence of permanent teeth
What % of people have congenital absence of teeth?
4-6%
What are the most common congenitally absent teeth?
Mandibular 2nd premolar, maxillary lateral incisor, maxillary 2nd premolar, mandibular central incisors
What is the % incidence of supernumerary teeth?
1-2%
Where are supernumerary teeth most commonly found?
Maxillary incisor region (mesiodens) and the premolar region
What are is the eruption order of the permanent dentition?
1/6, 2, 3, 4, 5, 7, 8
What are the eruption times of the central incisors in the permanent dentition?
Maxilla- 7-8
Mandible- 6-7
What are the eruption times of the lateral incisors in the permanent dentition?
Maxilla- 8-9
Mandible- 7-8
What are the eruption times of the canines in the permanent dentition?
Maxilla- 11-12
Mandible- 9-10
What are the eruption times of the 1st premolars in the permanent dentition?
Maxilla- 10-11
Mandible- 10-12
What are the eruption times of the 2nd premolars in the permanent dentition?
Maxilla- 10-12
Mandible- 11-13
What are the eruption times of the 1st molars in the permanent dentition?
Maxilla- 6-7
Mandible- 6-7
What are the eruption times of the 2nd molars in the permanent dentition?
Maxilla- 12-13
Mandible- 11-13
What are the eruption times of the 3rd molars in the permanent dentition?
Maxilla- 17-21
Mandible- 17-21
What is the complete eruption order in the permanent dentition?
1 mandible, 6 mandible and maxilla, 1 maxilla, 2 mandible, 2 maxilla, 3 mandible, 3 maxilla, 4 maxilla, 4 mandible, 5 maxilla, 5 mandible, 7 mandible, 7 maxilla, 8 maxilla and mandible
What happens to the arch length during eruption?
The arch length increases slightly on eruption of the permanent incisors due to jaw growth and increased proclination of the permanent incisors
There is an increase in arch length to accommodate additional permanent molars
From 6-1 arch length decreases after primary molars are shed
What length is the permanent incisors?
Maxillary 7mm
Mandibular 5mm
How many degrees more proclined are permanent incisors than primary incisors?
10-15 degrees
What happens to the arch width during eruption?
Little change in the primary dentition
Increases on eruption of the permanent incisors
Once the permanent incisors are erupted there is no further transverse growth of the arches
What happens to the arch height during eruption?
Juvenile occlusal equilibration- after teeth have erupted into the occlusion they must continue to erupt at a slower pace to match vertical skeletal growth
Adult occlusal equilibration- once the adolescent growth spurt has passes the teeth continue to erupt to compensate for wear and the continued vertical skeletal growth
