1. Primary Dentition:Primary Dentition:
Anterior and PosteriorAnterior and Posterior
Howard Chi, D.M.D.Howard Chi, D.M.D.

2. Learning Objectives
• Generals of primary dentition
• Anatomy of primary anteriors
• Anatomy of primary posteriors
• Eruption patterns of primary
dentition and permanent dentition

3. Generals of
Primary Dentition

4. Primary
Dentition
* Primary teeth emerge in children between
the ages of 6 months and 2 years
* Beginning at age 6 these teeth are
gradually replaced by the permanent teeth

5. Primary
Dentition
* Primary teeth are often called deciduous
teeth
* From the Latin to fall off
* Common nicknames are “milk teeth” or
“temporary teeth”

6. Primary Dentition
* The teeth function an average of 8 years
for maxillary teeth
* The teeth function an average of 7.6 years
for mandibular teeth
* Hold an important role in reserving space
for permanent teeth

7. Important Functions Of
Sound Primary Teeth
1) Efficient mastication of food
2) Maintenance of a normal facial appearance
3) Formulation of clear speech
4) Maintenance of proper diet
5) Avoidance of infection and pain
6) Maintenance of space and arch continuity

8. Eruption
Time Of
Primary
Dentition
* First primary teeth to erupt are usually
mandibular central incisors at about 6
months
* Last teeth to erupt are the maxillary
second molars around 24 months

9. Mixed
Dentition
* First permanent teeth to
erupt are the mandibular
first molars and then
maxillary first molars
* They appear distal to the
primary second molars
* With their eruption
commences the mixed
dentition period

10. Mixed Dentition
* The roots of primary teeth are completely
formed 1 year after emergence of the
crown into the mouth
* The roots are short lived beginning to
resorb in just three years
* After exfoliation, the permanent teeth
emerge within a few months

11. General
Characteristics Of
Primary Teeth
1) Primary teeth are smaller in size than
permanent teeth
2) They are whiter in color than the
analogous permanent teeth
3) They are less mineralized than permanent
teeth

12. General
Characteristics Of
Primary Teeth
4) They have shorter crowns with respect to
their roots
5) Crowns have a marked constriction at the
cervix
6) The enamel seems to bulge close to the
cervical line, rather than gradually tapering

13. General
Characteristics Of
Primary Teeth
7) The layers of enamel and dentin are
thinner than on permanent teeth
8) The pulp cavities are proportionally larger
9) Primary teeth exhibit fewer anomalies
10) The crowns appear bulbous, often with
labial or buccal cingula

14. Primary
Anterior Dentition

15. General
Characteristics
Of The
Anterior Teeth
1) Usually no depressions on the labial
surface of the crowns of incisors
2) There are no mamelons on the incisal
edges
3) Facial cervical ridges are prominent

16. General
Characteristics
Of The
Anterior Teeth
4) Cingula are prominent and occupy 1/3
cervicoincisal length
5) The roots are long in proportion to the
crown length, and narrow mesiodistally
6) The roots bend labially in their apical 1/3
to 1/2 as much as 10 degrees

17. Proximal Aspect Of
Primary Incisors
Root Shape
* The roots of maxillary incisors are S-shaped,
bending toward the lingual in the cervical third
to half and then bend labially in the apical half
* The roots of mandibular incisors are straight in
the cervical half and bend labially in their
apical half
* This bend help provide space for the developing
teeth

18. Primary
Canines
Uniqueness of Contact Areas:
* Mesial and distal contacts are in the middle
third of the crowns, with the mesial being
located more cervical than the distal (a
condition unique to the tooth and one other,
which tooth?)
D

19. Primary Canines
Primary canine root:
* Are bulky in the middle and cervical
thirds, tapering in the apical third where
they bend labially

20. Primary
Posterior Dentition

21. 1) The molar crowns are wider mesiodistally, yet shorter
cervico-occlusally
2) The second molars are much larger than the first molars
3) The molar crowns have a narrow chewing surface
4) The molar occlusal anatomy is shallow (cusps are short)
5) The buccal cusp tips are not pointed and their slopes meet at
very obtuse angles
General
Characteristics
Of The
Posterior Teeth

22. 6) There are few grooves or depressions in the crowns
7) The root furcations are near the crown, with little or no root
trunk
8) The roots are widely spread beyond the outlines of the
crown
9) The roots are thin and slender
10) The second molar roots are spread more widely than the
first molar roots
General
Characteristics
Of The
Posterior Teeth

23. Primary Molars
* Primary first molars are smaller than primary
second molars
* Primary first molars are quite unique in their shape
* Primary second molars have considerable likeness
to permanent first molars
* Maxillary molars have three roots and mandibular
possess two

24. Primary Maxillary
First Molar
Uniqueness for primary maxillary first molar:
1. Resembles a permanent premolar*
2. Groove pattern is “H” shape

25. Primary Mandibular
First Molar
Uniqueness for primary mandibular first molar:
1. Resembles no other tooth in either primary or
permanent dentition*
2. Two roots: Mesial and distal. With the Mesial
root wider and longer than the distal (opposite
of permanent mandibular molars (in length))

26. Eruption Patterns:Eruption Patterns:
Primary and PermanentPrimary and Permanent
DentitionDentition

27. Eruption and Resportion
• Eruption: Historically denotes the eruption of tooth
through the gingiva
• Resorption: The permanent tooth in its follicle
attempts to force its way into the position held by its
predecessor
• The pressure brought to bear against
primary root causes resorption of the root
until exfoliated

28. Dental Age
• Has been assessed on the basis of the
number of teeth at each chronological age
• Calcification of the organic matrix, root
formation, and tooth eruption are
important indicators of dental age
• Dentition is the single best physiological
indicator of chronological age in juveniles

29. Primary Tooth
Eruption Sequence
1) Central Incisors
2) Lateral Incisors
3) First Molars
4) Canine
5) Second Molars

30. Primary
Mandibular
Incisors
• Centrals erupt at a mean age of 6 months
• Laterals erupt at a mean age of 7 months
(occasionally, all lower incisors will erupt
before the maxillary incisors)
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31. Primary
Maxillary
Incisors
• Maxillary central follow mandibular
central by mean age of 1 months and
erupt at 7 months
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32. • Laterals erupt at a mean age of 9
months
Primary
Maxillary
Incisors
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33. Primary
First
Molars
• First molars erupt at a mean age 12-14
months
• Mandibular usually erupts first
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34. Primary
Canines
• Mandibular canine erupts at a mean age of
16 months
• Maxillary canine erupts at mean age of 18
months
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35. Primary Second Molars
• Mandibular second molars erupt at a
mean age of 20 months
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36. • Maxillary second molars erupt
at a mean age of 24 months
Primary Second Molars
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37. Succedaneous Teeth
(Teeth that replace a primary
predecessor)
1) Permanent Incisors
2) Permanent Canines
3) Permanent Premolars

38. Permanent First Molar
• Begin to calcify at about
the
time of birth
• Emerge distal to primary
second molar

39. • First molars are the first to erupt
• Occurs at 6 years of age and are
occasionally called "6-year molars"
Permanent
First
Molar
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40. Permanent Mandibular
Central Incisor
Second
permanent
tooth to
emerge
into the oral
cavity
• Mandibular central erupt at 6 years
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41. Permanent Maxillary
Central Incisor
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• Maxillary central at age7-8 years

42. Permanent Mandibualr
Lateral Incisor
• Mandibular lateral at 7-8 years (may erupt
along with the maxillary central incisors)
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43. Permanent Maxillary
Lateral Incisor
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• Maxillary lateral at age8-9 years

44. Permanent
Mandibular
Canine
• Mandibular canines erupt following the lateral
incisors between ages of 9-10 years
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45. Maxillary
First
Premolar
• Generally erupts at 10-11 years old
following the mandibular canine
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46. Maxillary Second And
Mandibular First Premolars
• Follow the maxillary first premolars
• Generally erupt at 10-12 years old
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47. Mandibular Second Premolar
And Maxillary Canine
• Follow the maxillary second premolars and
mandibular first premolars
• Generally erupt at age 11-12 years
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48. Permanent
Second
Molars
• Erupt at 11-13 years of age
• Mandibular usually erupts first
called "12-year molar"
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49. Permanent
Third
Molars
• Erupt at age 17 or later
• Considerable jaw growth required
to allow room for these teeth
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