Clinical development of the dentition Flashcards
What are the stages of development?
newborn, deciduous dentition, mixed dentition, permanent dentition
What structures do newborns have in place of teeth?
Gum pads
What are the shapes of the gum pads in newborns?
Upper is rounded while the lower is U-shaped
What is the typical bite of a newborn?
Anterior open bite (skeletal class 2)
What do skeletal classes 1/2/3 describe?
The antero-posterior (AP) jaw relationship
What is a skeletal class 1?
the mandible is 2-3 mm posterior to the maxilla
What is skeletal class 2?
Mandible is retruded relative to the maxilla
What is skeletal class 3?
The mandible is protruded relative to the maxilla
What are natal teeth?
Teeth present at birth or erupt soon after that are unrelated to the deciduous dentition (separate series)
Example of one of the most serious dental developmental disorders?
cleft lip and palate (can be unilateral or bilateral cleft)
Signs that someone was born with a cleft lip and palate?
Scar in palate, narrow maxilla, rotated teeth, primary retained teeth, absence of maxillary lateral incisors
What time period does the deciduous dentition usually erupt withing?
6 months - 3 years
Do the upper or lower deciduous dentition erupt first?
Lowers erupt before uppers
In which order do the deciduous teeth erupt?
a (1), b (2), d (4), c (3), e (5) - first primary molar erupts before canine as canine has a longer path of eruption
When do the As / 1s / central incisors erupt?
6-7 months
When do the Bs / 2s / lateral incisors erupt?
7-8 months
When do the Cs / 3s / canines erupt?
18-20 months
When do the Ds / 4s / first molars erupt?
12-15 months
when do the Es / 5s / second molars erupt?
24-36 months
Difference between deciduous and primary dentition
Deciduous incisors more upright/flatter than permanent incisors, deciduous dentition more spaced, deciduous dentition has softer enamel
Why are deciduous teeth often worn towards the end?
Primary enamel is softer than secondary enamel. Therefore, with hypodontia, deciduous teeth won’t last in place of missing permanent teeth.
Why is spacing in the deciduous dentition important?
To prevent crowding in permanent dentition
Chance of crowding in permanent dentition if there is no spacing in deciduous dentition
66%
Chance of crowding in permanent dentition if there is <3mm total space in deciduous dentition
50%
Chance of crowding in permanent dentition if there is 3-6mm spacing in deciduous dentition
20%
How much spacing in the deciduous dentition is preferrable to ensure no chance of crowding in permanent dentition?
> 6mm
At what ages is there a mixed dentition?
Approx 6-13
Which teeth erupt ages 6-8.5?
incisors and 6s (first permanent molars)
Which teeth erupt ages 10-12.5?
canines (3s), premolars (4, 5s) and second molars (7s)
How does the FDI notation work for deciduous teeth?
Quadrant number (5, 6, 7, 8) + tooth number
Which teeth erupt first at age 6?
31, 41 (lower central incisors) and 16, 26, 36, 46 (first permanent molars)
Which teeth erupt age 7?
11, 21 (upper centrals), 32, 42 (lower laterals)
Which teeth erupt age 8?
12, 22 (upper laterals)
Which teeth erupt age 11?
33, 43 (lower canines), 34, 44, 14, 24 (first premolars)
Which teeth erupt age 12?
13, 23 (upper canines), 15, 25, 35, 45 (second premolars)
17, 27, 37, 47 (second molars)
How is the increased space required for permanent incisors accommodated for?
Spacing of deciduous teeth, increase in inter-canine width, more proclined path of eruption of incisors.
What is the inter-canine width?
linear distance between cusp tips of canines in both mandible and maxilla
By how much does the inter-canine width increase by in the maxilla to accommodate the permanent incisors?
3.5 mm in maxilla
By how much does the inter-canine width increase by in the mandible to accommodate the permanent incisors?
3.0 mm in mandible
How does the AP arch length increase to accommodate for permanent incisors?
The permanent incisors are more proclined compared to the upright primary incisors.
What abnormalities during tooth eruption would require investigation?
Abnormal eruption sequence or a delay of more than 6 months between the eruption of a L and R tooth (asymmetrical eruption)
Possible cause of delayed eruption of teeth
supernumerary teeth may be present which are blocking the path of eruption of the permanent teeth. Surgical extraction of supernumerary teeth required.
Name of condition in which a tooth is abnormally large
macrodontia
Possible causes of macrodontia
splitting of 1 tooth germ into 2, or fusion of 2 tooth germs (may have 2 pulp chambers and be difficult to slim down)
What is hypodontia?
Congenital absence of one or more teeth
