Anatomy - Outcome 5 Flashcards
How many primary teeth?
20 - 10 on each arch
Eruption sequence of primary teeth
Eruption begins mandibular central incisor at approximately 6 months.
RULE: mn > mx
a) 1’s 6-10 months
b) 2’s 7-10 months/9-12 months
c) 4’s 12 -18 months
d) 3’s 16-22 months
e) 5’s 20-32 months/24-32 months
Sequence 1, 2, 4, 3, 5
Why are development/growth of primary teeth essential?
The development and growth of the primary teeth are essential because they influence arch growth and provide stimuli for the formation of arch space for the permanent teeth, which are larger and more numerous
Effects of premature loss of baby teeth?
Premature loss of primary teeth, especially canines and molars may result in malocclusion or malpositioning of the permanent teeth . The development of the arches is generally sufficient to accommodate the increased number and size of permanent teeth. If arch development is not in accord with the size of the developing teeth, “crowding” or “diastema” (space between the teeth) may occur. Finally, primary teeth are needed for speech articulatio
What is exfoliation ?
This process of shedding the deciduous teeth and replacement with permanent teeth is called exfoliation
When does exfoliation begin?
Exfoliation begins 2-3 years after the deciduous root is fully formed. The root begins to resorb at its apical end and resorption continues until the entire root has disappeared and the tooth falls out
What age do primary teeth erupt? roughly
The primary teeth begin to erupt at about six months of age and should all be present by 2-2 1/2 years of age.
Primary Teeth Characteristics - differing from permanent
-Anterior teeth have smaller crowns and roots
-Have no mamelons
-Molars are wider mesial to distal than permanent bicuspids
-Narrower roots and longer in comparison with the crown length
-Narrow cementoenamel junction
-The cervical ridge of enamel at the cervical third of the crowns of deciduous anterior teeth are very prominent labially and lingually.
-Buccocervical ridges of molars are much more pronounced creating a more bulbous or “bell-shaped” appearance
-Roots are more slender and longer and flare apically to allow room in between for the developing permanent tooth crowns.
-Lighter in colour more white with a bluish cast
-Pulp chambers are large compared to crown size
-Pulp horns extend more occlusally
Less dense pulp
Less dense enamel with inconsistent depth
Primate space
The term “primate spaces” refers to the space mesial to the maxillary cuspids and distal to the mandibular cuspids.
mandi primate space is between cuspid and first molar
maxi primate space is between lateral incisor and cuspid
Leeway space
The term “leeway space” refers to arch length space that is gained due to the fact that permanent bicuspids are smaller mesial-distally than the primary molars. This space becomes apparent as the primary molars exfoliate and are replaced by their permanent successors
Mesial drift
Growth also allows the possibility of leeway space but this is offset by the phenomenon called “mesial drift”. The first permanent molar tends to move mesially; therefore, the amount of space reserved for the bicuspids is reduced
Mesial Step
Most children have a mesial step between the distal surfaces of the second primary molars. By this we mean, the lower molars are situated more mesial than their maxillary counterparts (Fehrenbach & Popowics, 2020).
flush terminal plane
A smaller but still large group of children exhibit a flush terminal plane, with the distal surfaces of the primary second molars even with each other
distal step
A small minority has a distal step in which the mandibular molars are situated more distally than their maxillary counterparts
