Development of the teeth and occlusion

1. PEDODONTICS
DEVELOPMENT AND MORPHOLOGY
OF THE TEETH AND OCCLUSION
1
Dr. Amal A. A. Kader
Pediatric Dentist

2. DEVELOPMENT AND MORPHOLOGY
OF THE TEETH AND OCCLUSION
Introduction -
Calcification -
Importance of Primary teeth -
Eruption -
Principal morphological characteristics of primary teeth -
Morphologic differences between primary and permanent teeth -
Normal occlusion in children -
2

3. The development
of the human tooth
can be observed
as early as the sixth week
. of embryonic life
3

4. Calcification
All primary teeth
At birth and 6
months 6 and 3 1
year 1 2
years 2 4
years 3 and 7 5
years 9 8
4

5. Importance of Primary Teeth
Preparation of the food for digestion and assimilation . 1
Maintenance of space for the permanent teeth . 2
Helps to growth and development of the jaws . 3
Helps to the development of speech . 4
Aesthetic function . 5
5

6. ERUPTION
Each tooth stars to move towards occlusion
at the time of crown completion and beginning
of root formation
Pre-eruptive phase: in which the tooth root begins its formation . 1
. and begins to move toward the surface of the oral cavity
Eruptive phase: is the time of gingival emergence, and about ½ or . 2
. the root is formed 2/3
6

7. ERUPTION
Age
6 12 18 24 30
months
Tooth A B D C E
7

8. Calcification Eruption
All primary Age
At birth teeth and 6 Tooth
((months
months 6 and 3 1 A 6
B 12
year 1 2
D 18
years 2 4 C 24
years 3 and 7 5 E 36 -30
years 9 8
8

9. ERUPTION
Permanent Dentition
Upper 6 1 2 4 5 3 7
Tooth 6 7 8 9 10 11 12
Lower 6 1 2 3 4 5 7
9

10. Principal Morphological Characteristics
of individual primary teeth
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11. Maxillary Incisors
The mesiodistal diameter of the crown of the maxillary
central incisor is greater than the cervicoincisal lengt
The maxillary lateral incisor crown is smaller in all
dimensions and the length of the crown is greater
. than the mesiodistal width 11

12. Canine
The crown of the maxillary canine is more constricted
. at the cervical region than are the incisors
The canine root is more than twice the length of the
. crown
12

13. First maxillary primary molar
The mesiolingual cusp of the maxillary first molar is
the largest and sharpest
The distolingual cusp is poorly defined, small and rounded
13

14. Second maxillary primary molar
There is considerable resemblance between the
maxillary primary second molar and the
maxillary
. first permanent molar
There are two well-defined
buccal cusps, with a
developmental groove between
. them
The crown of the second molar is considerably larger
. than that of the first molar
14

15. First mandibular primary molar
The mandibular first primary molar doest not resemble
. any of the permanent teeth
; The mandibular first molar has two buccal cusps
. the mesial cusp is the larger of the two
15

16. Second mandibular primary molar
The mandibular second molar resembles the mandibular
first permanent molar
One of difference
between the crowns of the primary
molar and that of the first permanent molar is in the
distobuccal cusp because the distal cusp of the permanent
molar is smaller than the others two buccal cusps
16

17. Morphological differences between primary and
permanent teeth
Number: 20
Color: White
17

18. Morphological differences between primary and
permanent teeth
: Size
Primary teeth are smaller
in all dimensions
The mesiodistal width of primary
incisors and canines is less
The mesiodistal width of primary
molars is wider than their premolars
succesors
The thickness of enamel and dentine
in primary teeth is approximately half
Its thickness in permanent teeth 18

19. Morphological differences between primary and
permanent teeth
Crowns
The crowns of the primary teeth are
wider mesiodistally
The cervical ridge of enamel at the cervical
third of the anterior crowns is much more
prominent labially and lingually
The buccal and lingual surfaces of
primary molars converge sharply toward
the occlusal surface, forming a narrow
occlusal table
19

20. Morphological differences between primary and
permanent teeth
Crowns
The crowns of primary molars are bulbous
due to their markedly constricted necks
and pronounced cervical ridges on the
buccal aspect especially in the maxillary
and mandibular first molars
The enamel cap in primary teeth is thinner
and has nearly a constant depth
throughout the crown
The enamel cap in primary molars ends
abruptly at the cement enamel junction
20

21. Morphological differences between primary and
permanent teeth
Crowns
The enamel rods at the cervix slope
occlusally in primary teeth instead of
being oriented gingivally as in permanent
teeth
The interproximal contact between
primary molars is not a small round
area as in permanent molars but tends
to be a large ellipsoid and flattened area
21

22. Morphological differences between primary and
permanent teeth
Roots
The roots of primary anterior teeth
are narrower mesiodistally
The roots of the primary molars are
relatively longer and more slender
22

23. Morphological differences between primary and
permanent teeth
Pulp
The pulp chambers are large
The pulp horns are higher in primary
.molars, especially the mesial pulp horn
The root canals of primary molars
show more lateral branchings and apical
ramifications
Apical foraminae in primary teeth
is relatively wider
The pulp chamber will decrease
in size with an increase in age 23

24. Morphological differences between primary and
permanent teeth
Incisor spacing
Primate spaces
Overjet: 0
Overbite: Can be edge to edge until a
complete crown
Spee curve: There is not
24

25. Normal Occlusion in children
Occlusion at 3 years
Straight or flush terminal plane
Mesial step
Distal step
25

26. Normal Occlusion in children
Occlusion at 6 years
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27. Normal Occlusion in children
Occlusion at 8 to 9 years
With the eruption of the upper and lower
permanent incisors there is an increase in
depth of overbite
27

28. Normal Occlusion in children
Occlusion at 8 to 9 years
,Diastema between upper permanent central incisors
( which is normal for this age (ugly duckling stage 28

29. Normal Occlusion in children
Occlusion at 8 to 9 years
,Diastema between upper permanent central incisors
( which is normal for this age (ugly duckling stage
29

30. Normal Occlusion in children
Occlusion at 10 to 12 years
With the eruption of premolars, the vertical dimension
is increased which corrects the deep overbite
Closure of Leeway spaces
30

31. Normal Occlusion in children
Occlusion at 10 to 12 years
Diastema between upper central
incisors is closed
, With the eruption of premolars
the vertical dimension is increased
which corrects the deep overbite
Closure of Leeway spaces
31

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