Anatomy of Primary Teeth age group 6mnth to 6.ppt

anatomy of primary dention

1. Anatomy of Primary Teeth
Dr. Asad Rafique Memon

2. Lecture Overview
Primary Dentition
General Morphological considerations
Implications of Primary tooth morphology

3. Primary Dentition
20 primary teeth as compared to 32
permanent teeth
No premolars in the primary dentition
The primary molars are replaced by the
premolars
The permanent molars erupt distal to the
primary second molars

4. Eruption Patterns of Primary
Teeth
Sequence more
important than timing
Symmetrical pattern
Mandibular teeth erupt
first

5. Approximate Approximate
Eruption ScheduleEruption Schedule
““7+4” Guideline7+4” Guideline

6. 7 Months = First Tooth Erupts7 Months = First Tooth Erupts

7. 11 Months = 4 Erupted Teeth11 Months = 4 Erupted Teeth

7 months + 4 = 11 7 months + 4 = 11
monthsmonths

0 teeth + 4 = 4 teeth 0 teeth + 4 = 4 teeth

8. 15 Months = 8 Erupted Teeth15 Months = 8 Erupted Teeth

11 months + 4 = 15 11 months + 4 = 15
monthsmonths

4 teeth + 4 = 8 teeth 4 teeth + 4 = 8 teeth

9. 19 Months = 12 Erupted Teeth19 Months = 12 Erupted Teeth

15 months + 4 = 19 15 months + 4 = 19
monthsmonths

8 teeth + 4 = 12 teeth 8 teeth + 4 = 12 teeth

10. 23 Months = 16 Erupted Teeth23 Months = 16 Erupted Teeth

19 months + 4 = 23 19 months + 4 = 23
monthsmonths

12 teeth + 4 = 16 teeth 12 teeth + 4 = 16 teeth

11. 27 Months = 20 Erupted Teeth27 Months = 20 Erupted Teeth

23 months + 4 = 27 23 months + 4 = 27
monthsmonths

16 teeth + 4 = 20 teeth 16 teeth + 4 = 20 teeth

12. General Morphologic
considerations
Crown
Pulp
Root

13. Crown of Primary Teeth
Shorter
Narrower occlusal table
Constricted in the cervical
portion
Thinner enamel and
dentin layers
Enamel rods in the
cervical area directed
occlusally
Broad and flat contacts
Color is usually lighter

14. Crowns of Primary Teeth
Prominent mesio-buccal
cervical bulge seen in
primary molars
Incisors have no
developmental grooves
or mammelons

15. Primary Crown Anatomy
Mandibular Central Incisors-

Symmetrically flat when
viewed from buccal
Crown about 1/3 length of root
Cingulum present on lingual
surface
Mandibular Lateral Incisor
Similar form to central
Usually longer
Incisal edge slopes toward
distal and DI angle more
rounded

16. Primary Crown Anatomy
Maxillary Central Incisor
Only tooth that has a
greater mesiodistal width
than height
Prominent cingulum
Incisal edge straight
Maxillary Lateral Incisor
Similar form to cental
Smaller and DI angle
rounded

17. Primary Crown Anatomy
Maxillary Canine
Crown constricted at
cervical region
Well developed, sharp
cusp
Root is long, more than 2X
crown
Mandibular Canine
Similar form to maxillary
Crown shorter and
narrower labiolingually

19. Pulps of Primary Teeth
Relatively larger
Pulp horns are closer to
the outer surface
Great variation in size and
location
Mesial pulp horn is higher
Pulp chamber shallow
Form of the pulp follows
the external anatomy
Usually a pulp horn under
each cusp

20. Pulpal Anatomy

21. Roots of Primary Teeth
Roots of anterior teeth are
narrower mesio-distally
Posterior teeth have
longer and more slender
roots in relation to crown
size
Molar roots flare more as
they approach the apex
Apical foramina may be
larger and accessory
canals often larger and
more numerous

22. Implications of Primary tooth
morphology
The progress of caries is much faster in
the primary dentition, so incipient lesions
should be restored sooner than later!
Thinner enamel and dentin
Mesial pulp horn higher

23. Summary
Primary teeth have
Thinner enamel and dentin layers
Pulp horns closer to the outer surface
Mesial pulp horn much higher
Relatively larger pulps
Enamel rods direct slightly occlusally in the cervical
area
Cervical area is constricted significantly
Roots flare as they approach the apex
More tortuous and irregular pulp canals