DEVELOPMENT OF DENTITION AND OCCLUSION

1. DEVELOPMENT OF DENTITION and
occlusion
DONE BY:
AMRITHA JAMES, CRI

2. introduction
The purpose of knowing tooth
development is to know the course of
normal development, clinical features of
dentition and the most common
developmental disturbances.

3. Characteristics of human dentition
 Teeth of vertebrates are characterized
depending on:
 Mode of attachment
• Acrodont –teeth attached to
jaws by connective tissue
• Pleurodont- teeth are set
inside the jaws
• Thecodont – teeth are
inserted in a bony socket.
 Number of successive teeth
•Polyphyodont- multiple set
of teeth. Eg:sharks
•Diphyodont- two set of
teeth. Eg: humans
•Monophyodont- one set of
teeth. Eg: sheep, goat
 Shape of teeth
• Homodont – a
single type of
teeth
• Heterodont –
various types of
teeth

4. Dental formula
 Permanent dentition:
 Primary dentition:

5. Development of tooth
 Tooth formation occurs in the 6th week of
intrauterine life with the formation of
primary epithelial band.
 At about 7th week the primary epithelial
band divides into a lingual process called
dental lamina & a buccal process called
vestibular lamina.
 All deciduous teeth arises from dental
lamina, later the permanent successors arise
from its lingual extension & permanent
molars from its distal extension

6. DENTAL LAMINA
 Around 6th week the infero-lateral border of
the maxillary arch and the supero-lateral
border of the mandibular arch show localized
proliferation of the oral ectoderm resulting in
the formation of the horse shoe shaped band
of tissue called the dental lamina.
 The deciduous teeth are directly formed by
the proliferation of the lamina.
 The permanent molars develop as a result of
its distal proliferation.
 Succedenous teeth develop from a lingual
extension of the lamina.

7. ENAMEL ORGAN
 The ectoderm in certain areas of the dental
lamina proliferates and forms knob like
structures that grow into the underlying
mesenchyme.
 Each of these knobs represent a deciduous
tooth and is called the enamel organ.

8. development of teeth is divided into 3
stages
 Bud stage.
 Cap stage.
 Bell stage.

9. BUD STAGE
 This is the initial stage of tooth
development where the enamel organ
resembles a small bud.
 The enamel organ consists of peripherally
located low columnar cells and centrally
located polygonal cells.

10. CAP STAGE
 The tooth bud continues to proliferate
resulting in a cap shaped enamel organ.
 The outer cells of the cap covering the
convexity are cuboidal – the outer enamel
epithelium.
 The cells lining the concavity of the cap→
tall columnar – the inner enamel
epithelium.
 The polygonal cells between the outer and
the inner epithelium forms a cellular
network – the stellate reticulum.
 The ectomesenchymal condensation ie:-
dental papilla and dental sac are
pronounced during this stage.

11. BELL STAGE
 Due to the continued uneven growth of the enamel organ it acquires a bell
shape
 A few layers of flat squamous cells between the inner enamel epithelium and
the stellate reticulum – stratum intermedium.
 As the enamel formation starts the stratum intermedium collapses to a
narrow zone reducing the distance between the outer and the inner
epithelium.

12. LATE BELL STAGE
 Inner enamel epithelium → ameloblasts (
tall columnar cells ) → enamel.
 Dental papilla → odontoblast (cuboidal
cells then later columnar) → dentin.
 Outer enamel epithelium→ low cuboidal
cells → capillary network.
 Dental sac → circular arrangement of
fibers → periodontal ligament.
 The junction between inner enamel
epithelium and odontoblast →
dentinoenamel junction.

13. STAGES OF TOOTH BUD DEVELOPMENT:
 Initiation
 Phase of deciduous tooth- 5th month in
utero.
 Phase of permanent tooth-6th month
 Phase of accessional tooth-4th month in
utero to 4-5 yrs.
 Proliferation
 Histodifferentiation.
 Morphodifferentiation.
 Apposition.

14. NOLLA’S STAGES OF TOOTH DEVELOPMENT 1952:
0. Absence of crypt
1. Presence of crypt
2. Initial calcification
3. 1/3rd crown completion
4. 2/3rd crown completion
5. Crown almost completed
6. Crown completion
7. 1/3rd root completion
8. 2/3rd root completion
9. Root almost completed
10. Root completion

15. ERUPTION OF PRIMARY TEETH

16. ERUPTION OF PERMANENT TEETH

17. PRE EMERGENT ERUPTION
 Eruptive movements begin soon after the root
begins to form.
 Two processes are necessary for pre emergent
eruption:-
1. There must be resorption of bone and
primary tooth roots overlying the crown of
the erupting tooth.
2. The eruptive mechanism itself then must
move the tooth in the direction where the path
has been cleared.

18. POST EMERGENT ERUPTION
 Once the tooth erupts into the mouth it approaches the occlusal level and is
subjected to the forces of mastication.
 The amount of tooth eruption after the teeth have come into occlusion equals
the vertical growth of ramus in a patient who is growing normally

19. FACTORS AFFECTING DEVELOPMENT OF DENTITION
 Accelerating effect:
• Hyperthyroididm
• Hyperpituitarism
• Turners syndrome
 Decelerating effect:
• Hypothyroididm
• Hypopituitarism
• Downs syndrome
• Hypovitaminosis
• Amelogenesis
imperfecta
Systemic factors:

20. Local factors
 Aberrant tooth position
 Lack of space in the arch
 Early loss of predecessor
 Ectopic eruption
 Congenital absence of tooth
 Ankylosed tooth
 Retained deciduous
 Supernumerary tooth

21. PERIODS OF OCCLUSAL DEVELOPMENT
1. Pre-dental period.
2. The deciduous dentition period.
3. The mixed dentition period.
a. First transitional period
b. Inter transitional period
c. Second transitional period
4. The permanent dentition period

22. PRE - DENTATE PERIOD
(birth to 6 months)

23. GUM PADS
 The alveolar processes at the time of birth.
 Pink in colour, firm and are covered by a
dense layer of fibrous periosteum.
 The upper gum pad is horse shoe shaped
& the lower gum pad is U shaped and
rectangular, characterized by:

24.  Characteristics of gum pads:
• Dental groove:-separates the labiobuccal and the lingual portion.
• Transverse groove:-divides the gum pad into ten segments representing each
deciduous tooth.
• Gingival groove:-separates the gumpad from the palate and the floor of the
mouth.
• Lateral sulci:-present between the canine and the 1st molar.

25.  When the upper and the lower gum
pad are approximated there is a
complete overjet all around.
 This infantile open bite is
considered to be normal .
 It helps in sucking.

26. NATAL and NEONATAL TEETH
 Very rarely teeth are present at birth called
as Natal Teeth.
 If they erupt during the 1st 30 days then
they are called as Neonatal Teeth.
 90% of precociously erupted teeth are
primary, of which 85% are mandibular
incisors.

27.  Etiology:
• Superficial position of tooth germ
• Increased rate of eruption due to febrile incidents
• Hormonal stimulation
• Hereditary
 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

28. THE DECIDUOUS DENTITION

29. ERUPTION SEQUENCE
 The mandibular central incisors are the
first to erupt around 6-8 months of age.
 The sequence of eruption is :-
A – B – D – C – E.
 The primary dentition is usually
established by the age of 3 years.

30. 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

31. Primary
(lower)
First evidence of
calcification
(weeks in utero)
Crown completed
(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 19 31/4
1st molar 151/2 51/2 16(14-18) 21/4
2nd molar 18 10 27 3

32. CHARACTERISTICS OF DECIDUOUS DENTITION
I. Spacing
2 types of dentition are seen:
A) Spaced dentition: usually seen 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.

33.  Spacing invariably is seen mesial to the
maxillary canine and distal to the
mandibular canine.
 These spaces are called as Primate,
Simian Or Anthropoid Spaces.
 This space is used for early mesial shift.
 The amount of primate space in maxilla is
around 1.7mm. & in mandible 1.5 mm

34. B)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
 May indicate crowding in developing
permanent dentition Initially a deep bite may
occur due to the fact that the deciduous
incisors are more upright than their
successors.
Non- spaced dentition

35. II. 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:
1. Eruption of deciduous molars.
2. Attrition of incisors.
3. Forward movement of the mandible due to
growth
deep bite

36. III. Almost vertical inclination of
anteriors
IV. Ovoid arch form

37. MOLAR RELATIONSHIP
 The molar relationship in the primary dentition can be classified into 3 types:
1. Straight/flush terminal plane.
2. Distal step.
3. Mesial step.

38.  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
 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

39. Canine relationship
 Relationship of maxillary & mandibular
deciduous caninnes is one of the most stable
in primary dentition
 Classified as:
• Class 1 - mandibular canine
interdigitates in embrasure between
maxillary lateral and canine.
• Class 2 - mandibular canine
interdigitates distal to embrasure.
Class 1
Class 2

40. THE MIXED DENTITION
 The mixed dentition period begins at around 6 yrs of age with the eruption of the
1st permanent molar.
 This period can be divided into the following 3 phases:-
 1. 1st transitional period.
 2. Inter transitional period.
 3. 2nd transitional period

41. FIRST TRANSITIONAL PERIOD
 The first transitional period is
characterised by:
• Emergence of 1st permanent molar
• Incisor transition
• Establisment of occlusion

42. Emergence of 1st permanent molar
 The mandibular 1st molar is the first permanent tooth to erupt at
around 6yrs of age.
 The location and relation of the 1st permanent molar depends on
the distal relationship between the upper and lower 2nd deciduous
molars.

43. EARLY and LATE MESIAL SHIFT
 Early mesial shift:
The eruptive forces of the 1st permanent molar
is sufficient to push the deciduous 1st and 2nd
molars forward to close the primate spaces and
establish class Ι molar relationship.
 Late mesial shift:
In the cases when the primate spaces are absent
the permanent 1st molar drift mesially utilizing the
leeway space.
Maxilla: 0.9 mm/segment = 1.8 mm. Mandible: 1.7
mm/segment = 3.4mm.

44. Primary molar guidance
 Flush terminal plane → class Ι
(early and late mesial shift.)
 Mesial step → class Ι.
 Differential growth of mandible
in forward direction persists →
class ΙΙΙ.
 Distal step → class ΙΙ.

45. Exchange of Incisors
 During the 1st transitional period the
deciduous incisors are replaced by the
permanent incisors.
 The permanent incisors are considerably
larger then the deciduous teeth they replace.
 This difference between the amount of
space needed and the amount of space
available is called as Incisal liability.
 The incisor liability is about 7mm in the
maxillary arch and 5mm in the mandibular
arch..

46.  This is overcome by 3 factors :-
 1. Inter-dental spaces.
 2. Inter-canine width.
 3. Incisor inclination

47. INTER-DENTAL SPACES
 The physiologic spaces seen in the primary dentition are utilized to partly account
for the incisal liability.
 Maxillary arch- 4mm
 Mandibular arch- 3mm
 The permanent incisors are much more easily accommodated in normal
alignment in cases exhibiting adequate inter-dental spaces

48. INTER–CANINE WIDTH
 During the transition from the primary incisors permanent incisors an increase
in inter-canine width of both maxillary and mandibular arch is observed.

49. INCISOR INCLINATION
 The primary incisors are more upright than their permanent counterparts.
 Since the permanent incisors are more labially inclined they tend to increase the
dental arch perimeter.
 The incisal angle in primary dentition is 1500 whereas it is about 1230 in
permanent dentition.

50. INTER TRANSITIONAL PERIOD
 Contains both sets of dentition.
 Four permanent incisors, left and right first
permanent molar
 Deciduous canines and deciduous first and second
molars.
 This phase is relatively stable and no change
occurs.

51. SECOND TRANSITIONAL PERIOD
(9 to 10 years)

52.  Characterised by:
1. Emergence of bicuspids, cuspids,and second permanent
molars.
2. Establisment of occlusion

53.  The second transitional period is
characterized by the replacement of
deciduous molars and canines by the
permanent premolars and cuspids
respectively.
 The combined mesio distal width of the
permanent canines and premolars is less than
that of the deciduous canines and molars.
 This excess space is called leeway space of
Nance.
 1.8mm – maxillary arch.
 3.4mm – mandibular arch.

54. UGLY DUCKILNG STAGE (Broadbent
phenomenon)
 A transient or self correcting malocclusion is seen in the
maxillary incisor region between 8-10 yrs at the time of
eruption of the permanent canines.
 Its typical features are:
 Flaring of the lateral incisors.
 Maxillary midline diastema
 As the developing permanent canines erupt they displace the
roots of the lateral incisors mesially.
 This results in transmitting the force on roots of the centrals
which also get displaced mesially.
 Hence a distal divergence of the two centrals causes midline
spacing.

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

56. THE PERMANENT DENTITION PERIOD
 The permanent dentition is
considered when all permanent teeth
are seen in the dental arches, often by
the age of 12 to 14 years.
 Eruption sequence:
Upper: 6-1-2-4-5-3-7-8
Lower: 6-1-2-3-4-5-7-8

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

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

59. Self correcting anomalies
Self correcting anomalies Correction(timing/factors
involved)
I. Predentate period
a)Retrognathic mandible Corrects with differential and
forward growth of mandible
b)Anterior open bite Eruption of primary incisors
c)Infantile swallowing pattern During the first year of life with
introduction of solid foods in diet

60. Self correcting anomalies Correction(timing/factors
involved)
II. Primary dentition
a)Anterior deep bite Corrects with:
• Eruption of deciduous molars
• Attrition of incisal edges
• Forward and downward growth
of mandible
b)Flush terminal plane • Eruption of first permanent
molar
• Late shift- leeway space
c)Spacing Eruption of first permanent molar
d)Edge to edge Eruption of permanent incisors

61. Self correcting anomalies Correction(timing/factors involved)
III. Mixed dentition
a)Anterior deep bite Proprioceptive response condition of
patient
b)Mandible anterior crowding • Tongue pressure
• Incrase in intercanine width
c)Ugly duckling stage Maxillary canine eruption
d)End on relation • With eruption of first permanent
molars
• Late mesial shift in non spaced
dentition
IV. Permanent dentition
Overjet and overbite • Decrease with eruption of
permanent molars
• Differential growth of mandible