The document discusses the development of occlusion from birth through adulthood. It begins by defining occlusion and describing an ideal occlusion. It then outlines the major periods of occlusal development: the neonatal period involving gum pads in infants; the primary dentition period when baby teeth erupt; the mixed dentition period involving both primary and permanent teeth; and the permanent dentition period when all adult teeth erupt. Key processes discussed include tooth eruption sequences, transitions between dentition periods, and changes to the dental arches that allow proper alignment of teeth.

1. DEPT. OF PEDODONTICS
GOVT. COLLEGE OF DENTISRY, INDORE
SUBMITTED BY:
PALLAVI TRIPATHI
ARVIND UIKEY
BDS FINAL YEAR

2. INDEX
 Introduction
 Evolution
 Periods of occlusal development
 Neo-natal period.
 Primary dentition period.
 Mixed dentition period.
 Permanent dentition period
 Conclusion
 References

3.  Term occlusion is derived from the Latin word,
“occlusio”
 “defined as the relationship between all the
components of the masticatory system in normal
function, dysfunction and parafunction.”
 An ideal occlusion is the perfect interdigitation of
the upper and lower teeth, which is a result of
developmental process consisting of the three main
events, jaw growth, tooth formation and eruption

4. EVOLUTION
 To develop a functional occlusion it became
necessary for the teeth and bones to develop
synchronously. Over a period of time there was loss
or fusion of cranial and facial bones, the number of
bones have reduced and the dental formula has
also undergone changes

5. PERIODS OF OCCLUSAL DEVELOPMENT
 Occlusal development can be divided into the
following development periods:
o Neo-natal period.
o Primary dentition period.
o Mixed dentition period.
o Permanent dentition period.

6. NEONATAL PERIOD
(LASTS UPTO 6 MONTHS AFTER BIRTH)

7. GUM PADS
•Alveolar processes at the time of birth- gum pads.
• Pink in colour, firm and are covered by a dense layer of fibrous periosteum
Gum Pads

8.  The gum pad soon gets segmented by a
groove called transverse groove, & each
segment is a developing tooth site.
 The pads get divided into ‘labio-buccal’ &
‘lingual portion’, by a dental groove.
 The groove between the canine and the 1st
molar region is called the lateral sulcus,
useful for judging the inter arch relationship
at a very early stage

9. RELATIONSHIP OF GUM PADS
oMandibular lateral sulci lies posterior to maxillary lateral sulci.
o Mandibular functional movements are mainly vertical, and to a little extent
antero-posterior. Lateral movements are absent

10. NEONATAL JAW RELATIONSHIP
 A ‘precise bite’ or jaw relationship is not yet seen.
Therefore, neonatal jaw relationship cannot be
used as a diagnostic criterion for reliable prediction
of subsequent occlusion in the primary dentition.

11. STATUS OF DENTITION AT BIRTH

12. Natal,Neonatal & Pre-erupted Teeth
Natal Teeth (Present at Birth)
Neonatal Teeth (Erupted during the 1st month)
Pre-erupted (Erupting during the 2nd & 3rd month)
Clinical Significance
Difficulty to mother during breast feeding
Remove only if they are superneumeraries or if they
are loose enough that there is danger of exfoliation

13. One week old boy with two neonatal teeth

14. (From around the 6th month to 6 years)

15. SEQUENCE OF
ERUPTION
 A
 B
 D
 C
 E

16. Primary
(upper)
First evidence of
calcification
(Weeks in utero)
Crown
completed
(months)
Eruption
(months)
Root
completed
(years)
Central 14 (13-16) 11/2 10 11/2
Lateral 16 21/2 11 2
Canine 17 9 19 31/4
1st molar 151/2 6 16 21/2
2nd molar 19 11 29 3
Chronology of Primary
Dentition

17. Primary
(Lower
First evidence
of calcification
(Weeks in
utero)
Crown
completed
(months)
Eruption
(months)
Root
complete
d
(years)
Central 14 (13-16) 21/2 8(6-10) 11/2
Lateral 16 3 13( 10-
16)
11/2
Canine 17 9 20(17-23) 31/4
1st molar 151/2 51/2 16( 14-
18)
21/4
2nd
molar
18 10 27 3

18.  Some of the characteristic clinical features of
deciduous dentition are:
1. Both the dental arches are half round in shape or
ovoid.
2. Almost no curve of Spee is present.
3. Shallow cuspal interdigitation.
4. Slight overjet.
5. Deep bite.
6. Vertical inclination of the incisors.
7. Spaced dentition.
8. Different maxillo-mandibular relations like flush,
mesial & distal terminal planes.
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19. MIXED DENTITION
PERIOD
(AROUND 6 YEARS- 12 YEARS)
The mixed dentition period can be divided into three phases:
o First transitional period.
o Inter-transitional period.
o Second transitional period.

20. FIRST TRANSITIONAL PERIOD
 The first transitional period is characterized by
the emergence of the first permanent molars and
the exchange of deciduous incisors with the
permanent incisors.
Emergence of first permanent molars
 The mandibular first molar is the first permanent
tooth to erupt at around 6 years of age.
 The location and relationship of the first permanent
molars depends much upon the distal surface
relationship between the upper and the lower second
deciduous molars. 20

21.  The mesio-distal relation between the distal surfaces
surfaces of the upper and lower second deciduous
molars can be of 3 types:
A. Flush terminal plane
B. Mesial step terminal plane
C. Distal step terminal plane
.
21

22. A. Flush terminal plane, B. Distal step terminal plane, C.
mesial terminal plane

23. EXCHANGE OF INCISORS

24. TRANSITION OF INCISORS
The incisal liability is over come by the
following factors:
Interdental physiological spacing in the primary incisor region. (4
mm in maxillary arch & 3 mm in mandibular arch)

25. Increase in inter-canine arch width:
Significant amount of growth occurs with the eruption of incisors and
canines.

26. Increase in anterior length of the dental
arches:
Permanent incisors erupt labial to the primary incisors to obtain an
added space of around 2-3 mm.

27. Change in
inclination of
permanent incisors:
Primary teeth are upright but
permanent teeth incline to the
labial surface, thus decreasing
the inter-incisal angle from
about 151 degrees in the
deciduous dentition to 124
degrees in the permanent
dentition. This increases the
arch perimeter.

28. INTER-TRANSITIONAL PERIOD
 In this period the maxillary and mandibular arches
consist of sets of deciduous and permanent teeth.
 Between the permanent incisors and the first
permanent molars are the deciduous molars and
canines.
 This phase during the mixed dentition period is
relatively stable and no change occurs.
28

29. Fig: OPG of mixed dentition
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30. SECOND TRANSITIONAL PERIOD
 The second transitional period is characterized by
the replacement of the deciduous molars and
canines by the premolars and permanent cuspids
respectively.
 The combined mesio-distal width of the permanent
canines and premolars is usually less than that of
the deciduous canines and molars. The surplus
space is called leeway space of Nance.
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31. LEEWAY SPACE OF NANCE
• Described by Nance in 1947
Maxilla: 0.9 mm/segment = 1.8 mm.
Mandible: 1.7 mm/segment = 3.4mm.

32. UGLY DUCKLING STAGE
 Sometimes a transient self-correcting
malocclusion is seen in the maxillary incisor
region between 8 to 9 years of age.
 This is a particular situation seen during the
eruption of the permanent canines.
 As the developing permanent canines erupt
they displace the roots of the lateral incisors
mesially. This results in transmitting the force
on to the roots of the central incisors, which
also get displaced mesially.
 A resultant distal divergence of the crowns of
the two central incisors causes a midline
spacing. This situation has been described by
Broadbent as the ugly duckling stage.
 This condition usually corrects by itself when
the canines erupt and the pressure is
transferred from the roots to the coronal area
of the incisors.
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33. 33

34. PERMANENT DENTITION PERIOD
 Permanent dentition forms within the jaws soon
after birth, except for the cusps of the first
permanent molars, which form before birth.
 Permanent incisors develop lingual or palatal to the
deciduous incisors and move labially as they erupt.
 Premolars develop below the diverging roots of the
deciduous molars.
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35. 35

36. CHRONOLOGY OF HUMAN PRIMARY TEETH
36

37. Permanent
(Upper)
First
evidence of
calcification
( weeks in
utero)
Crown
completed
(months)
Eruption
( months)
Root
completed
(years)
Central 3-4 mo 4-5 yr 7-8 yr 10
Lateral 10-12 mo 4-5 yr 8-9 yr 11
Canine 4-5 mo 6-7 yr 11-12 yr 13-15
1st premolar 11/2-13/4 yr 5-6 yr 10-11 yr 12-13
2nd premolar 2-21/4 yr 6-7 yr 10-12 yr 12-14
1st molar At birth 21/3-3 yr 6-7 yr 9-10
2nd molar 21/3-3 yr 7-8 yr 12-13 yr 14-16
3rd molar 7-9 yr 12-16 yr 17-21 yr 18-25
Chronology of Permanent Dentition

38. ERUPTION SEQUENCE
 The frequently seen sequences in the maxillary
arch (permanent):
6-1-2-4-3-5-7 or
6-1-2-3-4-5-7
 The frequently seen sequences in the mandibular
arch (permanent):
6-1-2-3-4-5-7 or
6-1-2-4-3-5-7
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39. THE PERMANENT DENTITION
The permanent incisors
develop lingual to the
deciduous incisors and move
labially as they erupt.

40. THE PERMANENT DENTITION
The premolars develop below
the diverging roots of the
deciduous molars.

41. THE PERMANENT DENTITION
At approximately 13
years of age all
permanent teeth
except third molars are
fully erupted.

42. Vertical overbite of about
one third the clinical
crown height of the
mandibular central
incisors. Overjet and
over bite decreases
throughout the second
decade of life due to
greater forward growth of
the mandible.

43. CONCLUSION
In its simplest of definition, occlusion is the way the maxillary and
mandibular teeth articulate, but in reality dental occlusion is a much
more complex relationship, because it not only involves the study of
the teeth, but also their morphology and angulations, the muscles of
mastication, the skeletal structures, the temporomandibular joint,
and the functional jaw movements. In addition to this, it also involves
the relationship of the teeth in centric occlusion, in centric relation,
and even during function, and because all this, requires
neuromuscular coordination, occlusion should also involve an
understanding of the neuromuscular systems, it is the responsibility
of we ‘pedodontists’ to have an adequate knowledge on these
subjects, to help us differentiate abnormal from normal, before
initiating therapy.

44. REFERENCES
 Orthodontics The Art and Science by S. I. Bhalajhi
 Textbook of Pediatric Dentistry by Nikhil Marwah
 Textbook of Pedodontics by Shobha Tandon
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