This document discusses the development of teeth over four periods: pre-dentition, primary dentition, mixed dentition, and permanent dentition. It describes the key developments that occur in each period, including the eruption of baby teeth and permanent teeth. For example, in the primary dentition period, the first teeth begin erupting around 6 months of age and the set is complete by 2.5-3.5 years. In the mixed dentition period, the first permanent molars erupt around age 6 and both primary and permanent teeth are present.

1. BY
Dr. ALVI FATIMA
MDS 1ST YEAR
DEPT OF PEDIATRIC & PREVENTIVE DENTISTRY 1

2. INDEX
 Introduction
 Development of tooth an overview
 Period of occlusal development
 Pre-dentition period
 Primary dentition period
 Mixed dentition period
 Permanent dentition period
 Developmental disturbances
 Conclusion
2

3. 3
Development of tooth an over-view

4. 4

5. 5

6. 6

7. 7

8. 8

9. 9

10. PERIOD OF OCCLUSAL
DEVELOPMENT
 Occlusal development can be divided into
following development period.
 Pre-dental period
 Primary dentition period
 Mixed dentition period
 Permanent dentition period
10

11. (LAST UPTO 6 MONTHS AFERT BIRTH)
11

12. GUM PAD
 The alveolar process at the time of birth are known as
gum pads.
 The gum pads are pink, firm and covered by a dense
layer of fibrous periosteum
12

13. 13

14.  They are horse shoe shaped and develop in two parts.
 They are labio-buccal portion and the lingual portion
 The two portion of the gum pads are separated from
each other by a groove called the dental groove.
 The gum pads are divided into ten segments by certain
grooves called transverse grooves.
 Each of this segments consist of one developing
deciduous tooth sac
14

15.  The transverse groove between the canine and
firs deciduous molar segment is called the
lateral sulcus.
 The sulci is useful in judging the inner-arch
relationship at a very early stage.
15

16.  The upper and lower gum pads are almost similar
to each other
 The upper gum pad is both wider and longer then
the mandibular gum pad
 When the upper and lower gum pads are
approximated, there is a complete overjet all
around
16

17.  The contact point of upper and Lower gum pads in
first molar region
 A space exist between them in the anterior region
 This infantile open bite is
normal and it helps n suckling.
17

18. NATAL AND NEO NATAL TEETH
 Very rarely teeth are found to have erupted at the
time of birth such teeth are known as natal teeth.
 Teeth that erupt during the first month of age are
called as neonatal teeth
 The natal and neo natal are mostly located in the
mandibular incisor region
18

19. 19

20. THE DECIDUOUS DENTITION
PERIOD
20
•The primary teeth begin to erupt at the age
of about 6 month
•The eruption of primary teeth is completed
by 21/2 - 31/2 years of the age

21. Eruption age and sequence of
deciduous teeth
 The timing of the tooth eruption is highly variable,
variation of 3 months is accepted as normal
 Sequence of eruption is
A – B – D – C – E
 Between 3-6 years of age, the dental arch is
relatively stable and very few changes occur
21

22. SPACING IN THE DECIDUOUS TEETH
 Spacing usually exist in deciduous teeth
 This space is known as the physiological or
developmental space
 This space is important for normal development of
permanent teeth
 If space is absent its an indication that crowding of the
teeth may occur when permanent teeth erupt
22

23.  The total space present may vary from 0-8mm with an
average of 4mm in maxillary arch
 1-7mm in mandibular arch with an average of 3mm
23

24.  Spacing seen mesial to
maxillary canines and
distal to the mandibular
canines are wider than in
other spaces.
 These physiologic spaces
are called Primate Spaces
or Simian Spaces.
 They help in placement of
canine cusp of the
opposing arch.
 This space is used for
early mesial shift.
24
Primate Spaces or Simian Spaces.

25. THE FLUSH TERMINAL
 The mesio – distal
relationship between the
destal surface of the upper
and lower second deciduous
molars is called the terminal
plane
 A normal feature of
deciduous dentitions is a
flush terminal plane where
the distal surface of the
upper and lower second
deciduous molar are on the
same vertical plane
25

26. MESIAL STEP
 Distal surface of mandibular
deciduous second molar is
mesial to the distal surface
of maxillary deciduous
second molar.
DISTAL STEP
 Distal surface of
mandibular second
deciduous molar is more
distal to the distal
surface of the maxillary
second deciduous molar
26

27. DEEP BITE
 A deep bite may occur in the initial stage of development
 It is prominent by the fact that the deciduous incisor are more upright then their
successor
 The lower incisal edges often contact the cingulum area of the maxillary incisors
 This deep bite is later reduced by:
 Eruption of deciduous molars.
 Attrition of incisors.
 Forward movement of the mandible due to growth
27

28. MIXED DENTITION PERIOD
28

29.  The mix dentition period begins at
approximately 6 years of age with the eruption of
the first permanent molars
 During mixed dentition period, the deciduous
teeth along with the permanent teeth are
present in the oral cavity
29

30.  The mixed dentition period can be
classified into three phases
1. First transitional period
2. Inter transitional period
3. Second transitional period
30

31. FIRST TRANSITION PERIOD
 The first transitional period is
characterized by the emergence of the
first permanent molar and exchange of
the deciduous incisors with the
permanent
31

32. Emergence of the first
permanent molars
 Mandibular first moral is the first permanent molar to
erupt in the oral cavity at the age of 6.
 The location and relationship of the permanent molar
depends much upon the distal surface relationship
between the upper and lower second deciduous molar
32

33.  The mesio-distal relation between the distal
surface of the upper and lower second
deciduous molars can be of three types
a. Flush terminal plane
b. Mesial step terminal plane
c. Distal step terminal plane
33

34. 34

35. A. flush terminal plane
 The distal surface of the upper and lower second
deciduous molars are in vertical plane
 This type of relationship is called flush or vertical
terminal plane.
 This is a normal feature of the deciduous dentition
 Thus the erupting first permanent molars may also
be in a flush or end on relationship.
35

36.  For the transition of such an end on molar relation
to a class I molar relation the lower molar has to
move forward by about 3-5mm relative to the upper
molar
 This occur by utilization of the physiologic spaces
and lee way space in the lower arch and by
differential forward growth of the mandible
36

37.  The shift in the lower molar from a flush terminal
plane to a class I relation can occur in two ways
 They are designated as the early and the late shift
 Early shift occurs during the early mixed dentition
period
 The eruptive force of the first permanent molar is
sufficient to push the deciduous first and second
molar forward in the arch to close the primate space
and there by establish a class I molar relationship
37

38.  Since this occur early in the mixed dentition
therefore it is called early shift
 Many children lack the primate space and thus the
erupting permanent molars are enable to move
forward to establish class I relationship
 In this cases, when the deciduous second molar
exfoliate the permanent first molars drift mesially
utilizing the leeway space
 This occur in the late mixed dentition period and
thus called late shift.
38

39. B. Mesial step terminal plane
 In this type of relationship distal surface of the lower
second deciduous molar is more mesial then that of the
upper
 Thus the permanent molars erupt directly into Angles
class I occlusion.
 This type of mesial step terminal plane most commonly
occurs due to early forward growth of the mandible
 If the differential growth of the mandible in a forward
direction persist, it can lead to an Angles class III molar
relation
39

40. C. Distal step terminal plane
 This is characterized by the distal surface of the
lower second deciduous molar being more distal
to that of the upper
 Thus the erupting permanent molars may be in
the Angels class II occlusion
40

41. The exchange of incisors
 During the first transitional period the deciduous
incisors are replaced by the permanent incisor.
 The mandibular CI are usually the first to erupt
 The permanent incisor are considerably larger then the
deciduous teeth they replace
41

42.  This difference between the amount of space needed
for the accommodation of the incisor and the amount
of the space available is called incisor liability
 The incisor liability is roughly about 7mm in the
maxillary arch and about 5 mm in the mandibular arch
 The incisor liability over come by the following factors
42

43. a) Utilization of interdental spaces seen in the
primary dentition
 The permanent incisor much more easily
accommodated in normal alignment in cases
exhibiting adequate interdental spaces then in an
arch that has no space
43

44. b.) Increase in inter- canine width
 Significant amount of growth occurs with the eruption
of incisors and canines.
44

45. c.) change in the incisor inclination
 One of the difference between deciduous and
permanent incisor is there inclination
 The primary incisors are more upright then the
permanent incisors
45

46. INTER- TRANSITIONAL
PERIOD
 In this period the maxillary and mandibular
arches consist sets of deciduous and permanent
teeth
 This phase during the mixed dentition period is
relatively stable and no changes occurs
46

47. SECON TRANSITIONAL
PERIOD
 The Second transitional period is characterized by the
replacement of the deciduous molars and canine by the
premolars and the permanent cuspids respectively
 The combined mesio-distal width of the permanent
canine and the premolars is usually less then that of the
deciduous canine and molars.
 This surplus space is known as the leeways space
Nance.
47

48.  It is greater in the
mandibular arch (3.4mm,
1.7mm on each side of the
arch)
 And in maxillary it is 1.8mm
that is 0.9mm on each side of
the arch
 After the exchange of the
deciduous canine and
molars, the space available is
utilized for mesial drift of
the mandibular molars to
establish class I molars
relation
48

49. THE UGLY DUCKLING STAGE
 A self correcting malocclusion is seen in the maxillary
incisors region between 8-9 years of age
 This particular situation is seen during the eruption of
permanent canines
 As the permanent canine roots it displaces the root of the
lateral incisors mesially, and it results in transmitting the
force to CI, which also gets displaced mesially
 A resultant distal divergence of the crown of the two CI
causes a midline spacing
49

50. 50
•Crowns of canines in young jaws impinge on developing lateral
incisor roots, thus driving the roots medially and causing the
crowns to flare laterally.

51.  The roots of the central incisors are also forced
together, thus causing a maxillary midline diastema
51

52.  With the eruption of the canines, the impingement
from the roots shift incisally thus driving the incisor
crowns medially, resulting in closure of the diastema
as well as the correction of the flared lateral incisors.
52

53.  This situation is described by Broadbent as the ugly
duckling stage
 This condition corrects by itself when the canines
erupt and the pressure is transferred from the roots
to the coronal area of the incisors
53

54. THE PERMANENT DENTION
PERIOD
 The permanent dentition forms within the jaws soon
after the birth, except the first permanent molars that
form before birth
 The permanent incisors develop lingual or palatal to
the deciduous incisors and move labially as the erupt
 The premolars develop below the diverging roots of
the deciduous molars
54

55.  The sequence of eruption in permanent may
exhibit variation but most frequently seen in
maxillary arch is
6 – 1 – 2 – 4 – 3 – 5 – 7 or
6 – 1 – 2 3 – 4 - 5 – 7
 In case or mandibular
6 – 1 – 2 – 3 – 4 -5 – 7 or
6 – 1 – 2 – 4 – 3 – 5 - 7
55

56. Changes in Permanent Occlusion
56
Arch dimensional Changes:
•Arch length decreases to a surprising amount during the
late adolescent period.
•Fish found that Mandibular arch perimeter decreases by
5.0mm between 9-16 years whereas maxillary arch perimeter
decreased by about half the amount as it was in the
mandibular arch.

57. Occlusal changes:
 Both overjet and overbite decreases throughout the
second decade of life.
 It is due to greater forward growth of the mandible and
the eruption of permanent molars.
 Overbite decreases up to the age of 18 years by 0.5mm
 Overjet decreases by 0.7mm between 12 and 20 years
of age.
 The alveolar process may grow in height beyond 16
years of age.
57

58. FACTORS AFFECTING THE
DEVELOPMENT OF OCCLUSION
 GENERAL FACTORS:
 Skeletal factors: The position, size and relation of
bone in which the tooth develops.
 Muscle factors: The form and function of the muscle
which surround the teeth.
 Dental Factors: The size of the dentition in relation to
the size of the jaws.
 The position and relationship of the teeth within the
bone.
58

59.  LOCAL FACTORS:
 Aberrant developmental position of teeth
 The presence of supernumerary teeth.
 Hypodontia-The congenital absence of certain teeth.
 The effect of certain Habits.
59

60. MALOCCLUSION CAUSING HABITS.
 Thumb and finger sucking
 Tongue thrusting &Abnormal swallowing habits
 Lip and nail biting
 Mouth breathing
 Psychogenic habits and bruxism
60