1. By:
Piyush Verma
MDS 1st yr
Dept of Pedodontics & Preventive Dentistry

2. Index
•
Introduction
Evolution
• Periods of occlusal development
 Neo-natal period.
 Primary dentition period.
 Mixed dentition period.
 Permanent dentition period
• Developmental disturbances
• 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:
Neo-natal period.
o Primary dentition period.
o Mixed dentition period.
o Permanent dentition period.
o

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.
•

8. Gum Pads contd…
The gum pad soon gets segmented by
a groove called transverse groove, &
each segment is a developing tooth site.
•
The pads get divided into „labiobuccal‟ & „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. Gum Pads contd…
The upper gum pad is horse shoe
shaped & shows:
o Gingival groove: separates
gum pad from the palate.
o Dental groove: starts at the
incisive papilla, extends
backward to touch the
gingival groove in the
canine region & then
moves laterally to end in
the molar region.
o Lateral sulcus.

10. Gum Pads contd…
The lower gum pad is „U‟
shaped and rectangular,
characterized by:
o Gingival groove: lingual
extension of the gum
pads.
o Dental groove.
o Lateral sulcus.

11. Relationship of Gum Pads
Anterior open bite is seen at rest with
contact only at the molar region.
o
o
Complete overjet.
Class II pattern with maxillary gum
pad being more prominent.
o
Mandible is distal to the maxilla of 2.7
mm- male and 2.5- female. ( Sillman JH
1938)
o
oThe
range of variation of this distal
relationship is from 0 to 7 mm. .
( Sillman JH 1938)

12. Relationship of Gum Pads
o
Mandibular 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.

13. 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.

14. Status of Dentition at Birth

15. Precociously Erupted Primary
Teeth
Natal tooth
Neonatal teeth
Pre-erupted teeth‟ or „Early Infansive teeth‟ are teeth that
erupt during the 2nd or 3rd month.

16. Natal/neonatal teeth

Classification
Hebling (1997) classified natal teeth into 4 clinical categories:
1. Shell-shaped crown poorly fixed to the alveolus by gingival
tissue and absence of a root;
2. Solid crown poorly fixed to the alveolus by gingival tissue
and little or no root;
3. Eruption of the incisal margin of the crown through gingival
tissue
4. Edema of gingival tissue with an unerupted but palpable
tooth.

17. 
Gender


Predilection for females
Kates et al (1984) reported a 66% proportion for females
against a 31% proportion for males.

Etiology
It has been related to several factors, such as: Superficial position of the germ
 Infection or malnutrition
 Eruption accelerated by febrile incidents or hormonal
stimulation,
 Hereditary transmission of a dominant autosomal gene
 Osteoblastic activity inside the germ area related to the
remodeling phenomenon and hypovitaminosis

18. Natal/neonatal teeth

Associated syndromes

Hallerman-Streiff
Ellis-Van Creveld
Craniofacial dysostosis
Multiple steatocystoma
Congenital pachyonychia
Sotos Syndrome.






19. Natal/neonatal teeth

Complications

Interfere with feeding
Risk of aspiration
Traumatic injury to the baby‟s tongue
and/or to the maternal breast
Riga-Fede disease- oral condition
found, rarely in newborns manifests
as an ulceration on the ventral surface
of the tongue or on the inner surface
of the lower lip. Caused by trauma to
the soft tissue from erupted baby
teeth.



Riga-Fede disease

20. 
Diagnosis

A radiographic verification of the relationship
between a natal and/or neonatal tooth and
adjacent structures, nearby teeth, and the
presence or absence of a germ in the primary
tooth area would determine whether or not the
tooth belongs to the normal dentition ( Almeida
CM et al 1997)

Most natal and neonatal teeth are primary teeth
of the normal dentition and are not
supernumerary teeth ( Brandt Sk et al 1983)

Correspond to teeth of the normal primary
dentition in 95% of cases, while 5% are
supernumerary (Hawkins C 1932)

21. 
Treatment

If the erupted tooth is diagnosed as a tooth of the normal
dentition -- maintenance of these teeth in the mouth is the first
treatment option, unless this would cause injury to the baby
(Chow MH 1980, Roberts MW 1992)

When well implanted-- these teeth should be left in the arch
and their removal should be indicated only when they interfere
with feeding or when they are highly mobile, with the risk of
aspiration (Toledo AO 1996)

Reasons for removal -- The risk of dislocation and consequent
aspiration, traumatic injury to the baby‟s tongue and/or to the
maternal breast, (Kates GA et al 1984)

22. 
Martins et al (1998) suggested smoothing of the incisal
margin to prevent wounding of the maternal breast during
breast feeding.

If the treatment option is extraction, certain precautions should
be taken :
Avoiding extraction up to the 10th day of life to prevent
hemorrhage
Assessing the need to administer vitamin K before extraction
(0.5-1.0 mg IM)
Considering the general health condition of the baby
Avoiding unnecessary injury to the gingiva
Being alert to the risk of aspiration during removal.






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

24. Sequence of Eruption

25. Chronology of Primary Dentition
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
Wheelers…

26. Primary
(Lower
First evidence of Crown
calcification
completed
(Weeks in utero) (months)
Eruption
(months)
Root
completed
(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
Wheelers…

27. Status of Dentition
(during primary dentition period)

28. At around 5 – 6 Years
There are 48 teeth/parts of teeth present in the jaw. It is at this
time that there are more teeth in the jaws than at any other time.

29. Features Of Primary
Dentition
•
Spacing- 2 types of dentition are seen:
A) Spaced dentition - usually seen in the
deciduous dentition to accommodate the
larger permanent teeth in the jaws.
•
More prominent in the anterior
region, and are called ‘physiological
spacing’ or ‘developmental spacing‟.
• Absence of spaces in the primary
dentition is an indication that crowding of
teeth may occur when the larger
permanent teeth erupt.
•

30. Features Of Primary
Dentition contd…
Most subhuman primates
have it through out life and use
it for interdigitation of the
opposing canines. This space is
used for early mesial shift.
•
primate spaces’, ‘simian spaces’ or
‘anthropoid spaces’.

31. Features Of Primary Dentition
contd…




Non- spaced dentition
Teeth are present without any
spaces in between the teeth
Due to narrow dental arches or
if teeth are wider than usual
Usually indicates in developing
permanent dentition but it is not
always the case

32. Features Of Primary
Dentition contd…
Shallow overjet & overbite. Initially a deep bite may occur due to the fact that
the deciduous incisors are more upright than their successors. The lower incisal
edges often contact the cingulum area of the maxillary incisors. This deep bite
is later reduced by:
oEruption of deciduous molars.
oAttrition of incisors.
oForward movement of the mandible due to growth.

33. Features Of Primary
Dentition contd…
Almost vertical
inclination of anteriors.

34. Features Of Primary
Dentition contd…
Ovoid arch form.

35. Molar Relationship
The molar relationship in the primary dentition can be classified
into 3 types:
oStraight/flush terminal plane.
oMesial step.
oDistal step.

36. Flush Terminal Plane
If the distal surface of
maxillary and mandibular
deciduous second molars are in
the same vertical plane; then it
is called a flush terminal plane
•
Normal molar relationship in
the primary dentition, because
the mesiodistal width of the
mandibular molar is greater
than the mesiodistal width of
the maxillary molar.
•

37. Mesial Step
Distal surface of mandibular
deciduous second molar is
mesial to the distal surface of
maxillary deciduous second
molar.

38. Distal Step
Distal surface of mandibular
second deciduous molar is
more distal to the distal surface
of the maxillary second
deciduous molar

39. Canine relationship




Relationship of maxillary &
mandibular deciduous caninnes
is one of the most stable in
primary dentition
Classified as:
Class 1
Class 2
Class 1
Class 2

41. Mixed Dentition Period
(Around 6 years- 12 years)
The mixed dentition period can be divided into three
phases:
o
o
o
First transitional period.
Inter-transitional period.
Second transitional period.

42. First Transitional Period

43. Eruption of
st
1
Permanent Molar
The location & relation of the 1st permanent molar depends much
upon the distal surface of the upper & lower 2nd deciduous molar.

44. Transition to Class I Molar
Relation

45. Early Shift
Early shift occurs during the early mixed dentition period.
• Since this occurs early in the mixed dentition, it is called early shift.
•

46. Late Shift
This occurs in the late mixed
dentition period and is thus
called late shift.

47. Leeway Space of Nance
•
Described by Nance in 1947
Maxilla: 0.9 mm/segment = 1.8 mm.
Mandible: 1.7 mm/segment = 3.4mm.

48. • Although the deciduous posterior segment of teeth is larger than
the permanent segment, converse is true of the anterior segments
• Nance did not consider large difference in mesiodistal size
between the deciduous incisor teeth & their permanent
successors– arch needs to be looked in its totality
• Maxillary incisors, as a group in one quadrant– 3.2to 3.5 mm
larger
• Mandibular incisors, as a group in one quadrant – 2.4 to 2.5 mm
larger
• The latter figures balance out or cancel the 1.7 mm of so called
leeway space

49. • Moorrees
-- measurements of deciduous
& permanent teeth in the mouths obtained
by longitudinal studies, there is no leeway
space
• Total no. of permanent teeth destined to
replace total no. of deciduous teeth in an
average child – slighly less than 1mm
more space in mandibular arch, 6mm
more in maxillary arch
• 1.7 mm leeway space taken up by the
larger permanent incisors, requires more
distal eruption of permanent canines
• Allows reduction of incisor crowding in
mandibular arch

50. • If the permanent molars were allowed or even encouraged to
drift mesially and utilize the leeway space – no enough room in
the arch for the incisor segment
• Initially – permanent incisors are forced into a crowded position
• If molars are held stable, incisors will utilize the leeway
space, ultimately the average mandibular arch will have enough
room for proper alignment

51. Secondary spacing
• Term was coined by Baume
• Observed in closed primary dentition
• Secondary spacing can also occur
during the eruption of permanent
central incisors

52. Distal Step
When the deciduous second
molars are in a distal step, the
permanent first molar will
erupt into a class II relation.
This molar configuration is not
self correcting and will cause a
class II malocclusion despite
Leeway space and differential
growth.

53. Mesial Step
Primary second molars in
mesial step relationship lead to
a class I molar relation in
mixed dentition. This may
remain or progress to a half or
full cusp class III with
continued mandibular growth.

54. Influence of terminal plane on
st permanent
the position of 1
molar
Distal Step – 23.3%
incidence, abnormal,
Class II- 38.6%
Straight terminal plane
– 49.2% incidence, Class
I or II
Mesial Step - <2mm
26.7%, class I 58.9%
>2mm 0.8%. Class III2.5%

55. Exchange of Incisors

56. 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)

57. Transition of Incisors contd…
Increase in inter-canine arch width:
Significant amount of growth occurs with the eruption of
incisors and canines.

58. Transition of Incisors contd…
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.

59. Transition of Incisors contd…
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 parameter.

60. Inter-Transitional Period

61. Inter-Transitional Period contd…
Root formation of emerged
incisors, and molars
continues, along with
concomitant increase in
alveolar process height.

62. Inter-Transitional Period contd…
Resorption of roots of
deciduous canines and
molars.

63. Second Transitional Period

64. Ugly Duckling Stage
(Broadbent’s phenomenon)
Around the age of 8 - 9 years, a
midline diastema is commonly
seen in the upper arch, which is
usually misinterpreted by the
parents as a malocclusion.
Its typical features are:
oFlaring of the lateral incisors.
oMaxillary midline diastema.

65. Ugly Duckling Stage contd…
Crowns of canines on young
jaws impinge on developing
lateral incisor roots, thus
driving the roots medially and
causing the crowns to flare
laterally.

66. Ugly Duckling Stage contd…
The roots of the central incisors are also forced
together, thus causing a maxillary midline diastema.

67. Ugly Duckling Stage contd…
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.

68. Ugly Duckling Stage contd…
Hence this unaesthetic metamorphosis, eventually leads to an
aesthetic result.

69. Self correcting anomalies

70. Sequence of Eruption
The canines in the upper arch erupt only after the premolars
have replaced the deciduous molars, whereas the canine erupt
before the premolars in the lower arch.

71. Second Transitional Period contd…

72. Second Transitional Period contd…
Eruption of permanent second molars

Before emergence- second molars, oriented in a mesial &
lingual direction

Teeth- formed palatally, guided into occlusion by Cone
Funnel mechanism , upper palatal cusps (cone) slides into the
lower occlusal fossa (funnel)

Arch length is reduced by mesial eruptive forces

Thereby, crowding if present is accentuated

74. The Permanent Dentition
This period is marked by the
eruption of the four permanent
second molars.

75. Nolla’s Stages of Tooth Development

In 1960 Nolla studied the stages of tooth development using
panoramic & postero-anterior radiographs.
Moyers

76. The Permanent Dentition contd…
Calcification begins at birth
with the calcification of the
cusps of the first permanent
molar and extends as late as the
25th year of life. Complete
calcification of incisor crowns
take place by 4 – 5 years and of
the other permanent teeth by
6 – 8 years except for third
molars.

77. Chronology of Permanent Dentition
Permanent
(Upper)
First evidence Crown
of calcification completed
( weeks in
(months)
utero)
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
Wheelers…

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

79. The Permanent Dentition contd…
The permanent incisors
develop lingual to the
deciduous incisors and move
labially as they erupt.

80. The Permanent Dentition contd…
The premolars develop below
the diverging roots of the
deciduous molars.

81. The Permanent Dentition contd…
At approximately 13
years of age all
permanent teeth
except third molars
are fully erupted.

82. Features of Permanent
Dentition
Coinciding midline.
Class I molar relationship.

83. Features of Permanent
Dentition contd…
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.

84. Andrews keys to normal
occlusion

Key I – Molar relationship
MB cusp of the max 1st molar falls
into the mesiobuccal groove of the
mand 1st molar and that the distal
surface of the DB cusp of the upper
first permanent molar should make
contact and occlude with mesial
surface of the MB cusp of the lower
second molar.

85. Andrews keys to normal
occlusion
Key II Crown angulation (Tip)

The angulation of the facial axis of
every clinical crown should be
positive

The gingival portion of the long axis
of the all crowns must be distal than
the incisal portion.

86. Andrews keys to normal
occlusion
Key III Crown inclination

In upper incisors, the gingival
portion of the crown‟s labial surface
is lingual to the incisal portion.

In all other crowns, including lower
incisors, the gingival portion of the
labial or buccal surface is labial or
buccal to the incisal or occlusal
portion.

87. Andrews keys to normal
occlusion
Key IV – Rotations

The fourth key to normal
occlusion is that the teeth should
be free of undesirable rotations.

88. Andrews keys to normal
occlusion
Key V – Tight contacts

contact points should be tight
(no spaces).

In absence of abnormalities
such as genuine tooth size
discrepancies, contact point
should be tight.

89. Andrews keys to normal
occlusion
Key VI – Occlusal plane or curve
of spee
 The curve of Spee should have no
more than a slight arch.

Intercuspation of teeth is best
when the plane of occlusion is
relatively flat.

A deep curve of spee results in a
more contained area for the upper
teeth, making normal occlusion
impossible.

90. Andrews keys to normal
occlusion
Key VII – Correct tooth size or the bolton’s ratio

Bennett and McLaughlin in 1993 gave seventh key
to normal occlusion. i.e. the upper and lower tooth
size should be correct.

91. 
Roth (1981) added some functional keys to the previous six
keys to normal occlusion by Andrew:
a) Centric relationship and centric occlusion should be coincident.
b) In protrusion, the incisors should disclude the posterior teeth,
with the guidance provided by the lower incisal edges passing
along the palatal contour of the upper incisors.
c) In lateral excursions of the mandible, the canine should guide
the working side whilst all other teeth on that and the other side
are discluded.
d) When the teeth are in centric occlusion, there should be even
bilateral contacts in the buccal segments.

92. Abnormalities in dental arch
1.
2.
Arch Length Discrepancy
1.
Crowding
2.
Spacing
Deviation in no. of teeth1.
Absence of teeth ( Agenesis)
2.
Supernumerary teeth

93. Absence of teeth ( Agenesis)

Sequece of agenesis is –

3rd molar > Mand. 2nd premolars > Max
Lateral Incisors > Max. 2nd Premolar

94. Absence of teeth ( Agenesis)

95. Supernumerary teeth

96. Deviation in tooth size


Its relative in nature
All teeth combined > or < relative to size of jaws or
head.



Crowding
Spacing
Deviation in size of individual teeth

Tooth size Discrepancy

97. Tooth size Discrepancy

98. Ankylosis


Frequent in mand deciduous molars.
In permanent 2 types


Due to abnormal position within jaw
 Max perm. Canine
Due to lack of space
 Mand 3rd molar

99. 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
temperomandibular 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, and if we need to determine an abnormal course of
development, 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.

100. References
Handbook of Orthodontics: Robert E. Moyers.
• Orthodontics the art & science: S. I. Bhalajhi.
• Textbook of Orthodontics: M.S. Rani.
• Textbook of Pediatric Dentistry: S.G. Damle.
• Dental Anatomy, Physiology & Occlusion: Wheeler.
• Textbook of Pedodontics: Shoba Tandon.
• Textbook of Orthodontics: Samir E. Bishara.
• Contemporary orthodontics –Proffit
• Textbook of Pedodontics: Koch.
• Orthodontics principles and practice: T. M. Graber.
•