influence of development of dention and occlusion

1. DEVELOPMENT OF
DENTITION AND OCCLUSION
PRESENTED BY:
DR. PARUL SINGH

2. contents
 INTRODUCTION
EVOLUTIONARY CONCEPTS OF
OCCLUSION AND DENTITION
CHARACTERISTICS OF HUMAN DENTITION
PRENATEL DENTAL DEVELOPMENT
MOUTH OF NEONATE
DECICUOUS DENTITION STAGE
PRIMARY OCCLUSION
MIXED DENTITION STAGE
PERMANENT DENTITION
CONCLUSION

3. The formation of the teeth, development of the dentition
and growth of the craniofacial complex are closely related
in the prenatal as well as postnatal developmental period.
The formation, emergence , resorption and shedding of
deciduous teeth and the formation and emergence of
permanent teeth constitute a continuous series of
maturational events from before birth to adulthood
available for the assessment of dental maturation and even
for prediction of development in individuals.

4. The term dentition is used to describe the natural teeth
in the jaw bones. It may be defined as the type, number
and arrangement of the teeth or it refers to all the upper
and lower teeth collectively.
Humans have 2 sets of teeth during their lifetime---
Primary and Permanent.

5. Evolutionary Concept of dentition
During evolution several significant changes took place in
the jaws and teeth. When the reptilian evolve to
mammalian , the dentition went from
“polyphydont ” (many set of teeth)
“diphydont ” (only two sets of teeth)
&
“homodont ” (all of same teeth)
“heterodent”(different types of teeth like incisors,
canines , premolars and molars)

6. GRAPHICALLY THERE ARE 4 STAGES OF TOOTH
EVOLUTION:
1) The reptilian stage (haplodont)
2) Early mammalian stage (triconodont)
3) Triangular stage (tritubercular molars)
4) Quadritubercular molars

7. The reptilian stage (haplodont)- This stage represented by
simplest tooth form-single cone type confined to single hinge
movement of jaw.
Early mammalian stage(triconodont)- This stage exhibits
three cusps in the line of development of posterior teeth i.e.,the
larger or anthroplogically original cusp is centered with one
smaller cusp loacted anteriorly and another posteriorly.

8. Triangular stage (tritubercuar molars)- According to the
study evolutinary tooth development, three tricodont line are
changed to three cone shaped with teeth still by-passing each
other more or less, when the jaw opened or closed. These types
are found in dogs and other carnivorous animals.
Quadritubercular stage-projection is created on the triangular
form that finally occludes with the antagonist of the opposing jaw.
During this time as an accomodation to the changes in the tooth
form and anatomy, the articulation of the jaws changed
accordingly.

9. Teeth of vertebrates are characterized depending upon:
1)Mode of attachment
2)Number of successive sets
3) Shape of teeth

10.  THE WAY TEETH ARE ATTACHED TO JAW
--ACRODONT-- teeth are attached to the jaw by connective
tissue .
--PLEURODONT-- teeth are set inside the jaw
--THECODONT-- teeth are inserted into a bony socket
 DEPENDING ON NUMBER OF TEETH OF SUCCESSIVE SETS
--POLYPHYODONT-- teeth are replaced throughout life. E.g- shark
--DIPHYODONT-- two sets of teeth e.g- human beings
--MONOPHYODONT-- one set of teeth e.g-sheep, goat.

11. ACCORDING TO TYPE OR SHAPE OF TEETH
--HOMODONT– a single type of teeth
--HETERODONT– various type of teeth e.g- human beings.

12. ORIGINAL FORMULA OF
MAMMALS
 PRESENT DENTAL
FORMULA- TEETH NUMBER
REDUCED
Permanent dentition
I3/3, c1/1, pm4/4,
m3/3=44teeth
Decidous dentition
I2/2, c1/1, m2/2=20teeth
Permanent dentition
I2/2, c1/1, pm2/2, m3/3
=32 teeth
Deciduous dentition
I2/2, c1/1, m2/2 =20 teeth

13. PRENATAL DENTAL DEVELOPMENT
Tooth development, or odontogenesis, takes place in many stages,
which occur in a stepwise fashion for both dentitions.
Odontogenesis is a continuous process, and there is no clear-cut
beginning or end point between these stages. These stages include:
Dental lamina
Bud stage
Cap stage
Bell stage
Hertwig’s epithelial root sheath and root formation
Formation of enamel and dentin matrix.

14.  During these stages of odontogenesis, many physiological
processes occur which include:
• Initiation –dental lamina
•Proliferation- bud stage,cap stage and bell stage.
•Histodifferentiation-bell stage and formation of enamel and dentin
matrix
•Morphodifferentiation- bud stage, bell stage and formation of
enamel and dentin matrix
•Apposition- formation of enamel and dentin matrix

15. Not all teeth in each dentition begin to develop at the same time.
The initial teeth for both dentitions develop in the mandibular
anterior region, followed by the maxillary anterior region, and then
development progresses posteriorly in both jaws.
This posterior movement allows time for the jaws to grow to
accommodate the increased number of primary teeth, the larger
primary molars, and finally the overall larger permanent teeth.

16. A clear understanding of the stages of odontogenesis and their
physiological basis is important because developmental
disturbances can occur within any stages of odontogenesis,
affecting the physiological processes taking place. These
developmental disturbances can have ramifications that may affect
the clinical treatment of a patient.

18.  Odontogenesis of the primary dentition begins around the
6th week of prenatal development.
When the embryo is 6 weeks old, certain areas of basal cells
of the oral ectoderm proliferate more rapidly than do the cells
of the adjacent areas.
This leads to formation of the primary epithelial band
which is a band of epithelium that has invaded the underlying
ectomesenchyme along each of the horseshoe-shaped future
dental arches.
Initiation of odontogenesis

19.  At about 7 th week this primay epithelial band divides into an
inner(lingual) process called Dental lamina and an outer(buccal)
process called vestibular lamina.
The deciduous teeth formed by direct proliferation of dental
lamina. The permanent molar arise directly from a distal extension of
the dental lamina.
The successors of deciduous teeth develop from a lingual extension
of the free end of the dental lamina opposite to the enamel organ of
each deciduous teeth .

20.  Morphological changes in the dental lamina occurs in
following phases:
 Initiation of the entire deciduous dentition –during 2nd month
in utero
 Initiation of the entire permanent dentition –from 5th month in
utero to 4-5 yrs.
 Initiation of the 1st permanent molar–4 months in utero
 Initiation of the 2nd permanent molar-1 yr
 Initiation of the 3rd permanent molar-4 to 5 yrs

21. DENTAL LAMINA

22. Developmental disturbances during the initiation stage:
Lack of initiation results in the absence of single or multiple teeth
(partial) or all teeth (complete) which is called anodontia. Partial
anodontia is more common and most frequently occurs with the
permanent maxillary lateral incisors, 3rd molars and mandibular 2nd
premolars (listed in order of occurrence).

23. In contrast, abnormal initiation may result in the development of one
or more extra teeth or supernumerary teeth. These teeth are
commonly seen between the maxillary central incisors (mesiodens),
distal to the maxillary 3rd molars, and in the premolar region of both
dental arches (listed in order of occurrence).
They are initiated from the dental lamina and have a hereditary
etiology.

24. BUD STAGE
 The second stage of odontogenesis is
called the bud stage and occurs during
the 7th week of prenatal development for
the primary dentition.
This stage is named for an extensive proliferation or growth of the
dental lamina into buds or oval masses penetrating into the
underlying mesenchyme.

25.  The underlying mesenchyme also undergoes proliferation. A
basement membrane remains between the bud and the growing
mesenchyme.
Each of these little down growths from the dental lamina
represents the beginning of the enamel organ of the tooth bud of a
deciduous tooth. The area of ectomesenchymal condensation
adajacent to enamel organ is dental papilla.

26. Developmental disturbances during the Bud stage:
Abnormal proliferation can cause a single tooth (partial) or a
complete dentition to be larger or smaller than normal i.e.
macrodontia or microdontia respectively. Hereditary factors are
involved and teeth commonly affected with microdontia are the
permanent maxillary lateral incisors (peg lateral) and permanent 3rd
molars.

27. CAP STAGE
 The growth rate throughout the tooth
bud is not uniform & is more active at
the periphery.
The Cap stage begins by the 8th week
with the appearance of a concavity on
the deep surface of the bud.
The epithelium of the cap-shaped tooth organ enlarges &
proliferates into deeper connective tissues (ectomesenchyme).
Areas of increased cellular density give rise to non-enamel
portions of the tooth & its periodontal matrix.
The Tooth germ, consisting of the Enamel organ, Dental papilla
& Dental follicle can be identified.

28. Developmental disturbances during the Cap stage:
During the cap stage, the enamel
organ may abnormally invaginate
into the dental papilla, resulting in
dens-in-dente or dens
invaginatus. The teeth most
commonly affected are the
permanent maxillary incisors,
especially lateral incisors.

29. Another disturbance that can occur during the cap stage is
gemination. This occurs when a single tooth germ unsuccessfully
divides into two tooth germs. This results in a large single rooted
tooth with a common pulp cavity. The tooth exhibits “twinning” in the
crown area, with false macrodontia. It usually occurs in the anterior
region in either dentition and may be due to hereditary factors.

30. Union of two adjacent tooth germs may occur, possibly due to
pressure in the area resulting in fusion. The tooth is large, falsely
macrodontic. It usually occurs in anterior region and can present
problems in appearance and spacing.

31. Teeth may also have extra cusps, or tubercles, that appear as
small, round enamel extensions. They are noted mainly on the
permanent molars, especially 3rd molars. They may also be
present as a lingual extension on the cingulum of permanent
maxillary anterior teeth, especially lateral incisors and canines.
This disturbance may be due to trauma, pressure, or metabolic
disease that affects the enamel organ forming the crown area.

32. BELL STAGE
The 4th stage of odontogenesis
is the bell stage and occurs for the
primary dentition between the 11th
and 12th week of prenatal
development.
In the Bell stage, the Enamel
organ differentiates into :
-Inner enamel epithelium
-Stratum intermedium
-Stellate cells
-Outer enamel epithelium (OEE)

33.  Dental papilla cells differentiate into Odontoblasts & Inner
enamel epithelium cells into Ameloblasts. They deposit Dentin &
Enamel respectively, and withdraw from each other & the DE
junction.
 The OEE becomes discontinuous & allows entry of cells from
the Dental sac, while the Stellate cells are withdrawn to make room
for the Crown.When enamel formation is complete, the crown is
fully formed.

34. Developmental disturbances during the Bell stage:
 Both the cap and the bell stage involve the same
physiological processes i.e. proliferation, differentiation and
morphogenesis. Therefore the developmental disturbances
occurring during the cap stage can also occur in the bell stage.

35. Enamel hypocalcification : results in reduction in quality of the
enamel maturation. The teeth appear more opaque and yellower.
In dental fluorosis, enamel hypoplasia and hypocalcification may
occur together.
A certain type of enamel dysplasia, amelogenesis imperfecta, has a
hereditary etiology and can affect all teeth of both dentitions. In this
disturbance, teeth have very thin enamel portions that chip off easily.
Teeth undergo extreme attrition.

36. Root Formation:
 Just before the ameloblasts
deposit their matrix, the
Cervical loop lengthens due to a
proliferation of cells & forms
the Hertwigs epithelial root
sheath (determines no., size &
shape of roots ).
 Dentin matrix is deposited
against the root sheath &
covered by cementum due to the
invasion of cementoblasts,
which eventually form the PDL.
.

37. Developmental disturbances during Root formation:
Enamel pearls: Small group of
misplaced ameloblasts can cause
enamel to be abnormally formed on
the root surface. They appear as
small spherical enamel projections on
the root surface, especially at the
cementoenamel junction or in the
furcation area of molars.
 Epithelial rests of Malassez may proliferate into cysts or
tumors.

38. Dilaceration: An angulation, or a
sharp bend or curve, in the root of a
formed tooth is celled dilaceration. It
results from distortion of the Hertwig’s
root sheath due to injury or pressure.
Accessory roots:This disturbance
may also be due to trauma or pressure
that affects Hertwig’s root sheath. Any
tooth may be affected but 3rd molars are
most commonly affected.

39. formation of enamel and dental matrix
The final stages of odontogenesis include apposition, during
which the enamel and dentin are secreted in successive layers.
These tissues are initially secreted as a matrix, which is an
extracellular substance that is partially calcified yet serves as a
framework for later calcification.

40. Developmental disturbances during
formation of enamel and dental matrix
:Enamel dysplasia: Results when metabolic processes of
ameloblasts are disturbed. Local or systemic etiology. Local enamel
dysplasia may result from trauma or infection of a small group of
ameloblasts. Systemic dysplasia involves larger number of
ameloblasts and may result from systemic infections, nutritional
deficiencies, or dental fluorosis.

41. Enamel hypoplasia : results from
decreased quantity of enamel matrix.
The teeth appear with pitting and
grooves in the enamel surface. Enamel
hypoplasia can be involved in
Hutchinson’s incisors and Mulberry
molars due to the teratogenic potential
of congenital syphilis.

42. THE MOUTH OF THE NEONATE

43.  The gum pads
 Neonatal jaw relationship
 Status of dentition

44.  This is the period after birth during which the neonate does
not have any teeth.It usually lasts for 6 months after birth
 The alveolar processes at the time of birth are known as gum
pads.
They are pink, firm & are covered by a dense layer of fibrous
periosteum.
They are horse shoe shaped and develop into 2 parts:
Labio buccal portion
Lingual portion
The gum pads

45.  These are seperated from each other by a groove
called dental groove.
The gum pads are divided into 10 segments
by certain grooves called transverse
grooves.Each of these consists of 1 developing
decidious tooth sac.
The gingival groove seperates the gum pads
from the palate and the floor of the mouth.
The transverse groove between the canine &
1st decidious molar segment is called the lateral
sulcus.

46. The upper & lower gum pads are
almost similar to each other .
The upper gum pad is both wider as
well as longer than the mandibular gum
pad.
When the upper and lower gum pads
are approximated there is a complete
over jet all around.
Contact occurs between the upper and lower gum pads in the 1st
molar region & a space exists between the anterior region.
This infantile open bite is considered normal & it helps in suckling.

47. The status of dentition
 Natal teeth are present at birth whereas
neonatal teeth erupt during the 1st month.
 Pre-erupted teeth erupt during the 2nd or 3rd
month. These teeth are almost always
mandibular incisors, which frequently display
enamel hypoplasia.
 There are familial tendencies for such teeth.
They should not be removed in normal but
removed if supernumerary.

48.  SYNONYMS :
Congenital teeth
Fetal teeth
Pre deciduous
Dentitia precox
DEFINITION: masler and savara (1950)
Teeth that are present at birth are natal teeth and teeth that
emerge through the gingiva during first month of life are
neonatal teeth.

49. ETIOLOGY:
Superficial position of tooth germ
Infection or malnutrition
Febrile illness
Heredity
Hyper activity of dental lamina
Hypovitaminosis
Common teeth (90-99% primary)
Mand. incisors > maxillary incisors > mand cuspid > molars

50. CLINICAL FEATURES:
Normal or shell like structure.
Enamel hypoplasia
Occurs in pairs
No root growth
As root grows it becomes firmer
Ulceration of tongue.
TREATMENT:
Extraction
Trimming

51. Butler field theory
According to this, mammalian dentition can be divided into
four developmental fields.
The developmental fields include the molar, premolar , canine
and the incisor fields.
 Distal tooth in each field is the most susceptible to changes or
variations
Changes includes absence of tooth variation in size ,shape and
strusture. Accordingly, lateral incisor second premolar and
third molars are is more prone to variation in their group.

52. PRE EMERGENT ERUPTION
POST EMERGENT ERUPTION
PRE EMERGENT ERUPTION:
FOLLICULAR PHASE: Labial or buccal drift of the tooth
follicle within the bone.
Eruptive movements begin soon after root begins to form.
Thus in the “PRE EMERGENT SPURT PHASE”
eruption begins.

53. Two processes are necessary
1)There must be resorption of bone and primary tooth roots
overlying the crown of the erupting tooth.
2)The eruption mechanism itself then must move the tooth
in the direction where the path has been cleared.
POST EMERGENT ERUPTION:
EMERGES 3/4th of its root development is
complete.
EMERGES erupts rapidly approaches the
occlusal level and is subjected to masticatory forces. At this
point eruption slows.

54. POST EMERGENT SPURT
The stage of relatively rapid
eruption from the time a tooth
first penetrates the gingiva until
it reaches the occlusal level is
called as the POST EMERGENT
SPURT.
The phenomenon of this slow
eruption in this phase is called as
JUVENILE OCCLUSAL
EQUILIBRIUM.

55.  A final phase in tooth eruption .Ending of the
pubertal growth spurt
 Adult teeth continue to grow at a slow rate.
 Antagonist is lost, tooth erupts more rapidly.
 Thus eruption mechanism is capable of
producing tooth movement late in life.
 Wear of teeth is compensated by additional
eruption and facial height remains constant.

56. Theories of tooth eruption
 The mechanism that brings about tooth movement is still
debatable. But, few theories which have been given serious
consideration are:
1. Bone remodeling theory
2. Root growth theory
3. Vascular pressure theory
4. Ligament traction theory

57. Bone remodeling theory:
This theory supposes that selective deposition and
resorption of bone brings about eruption of tooth.
Root growth theory:
This theory states that proliferating root impinges on a
fixed base, the cushion-hammock ligament, thus converting
an apically directed force into occlusal movement.

58. Vascular pressure theory:
This theory supposes that a local increase in tissue fluid
pressure in the periapical region is sufficient to move the
tooth.
Ligament traction theory:
This theory states that the cells and fibers of periodontal
ligament pull the tooth in occlusion.

59. DECIDIOUS DENTATION STAGE
The mandibular central incisors are the first to develop in
deciduous dentition followed by other incisors.This takes
place at the period of 6 months after birth.
After 3-4 months around 10 months the mandibular and
maxillary first molars erupt.
Within 24-30 months the max & mandibular second molars
also erupt..at this stage primary dentition is complete.

60. Normal signs of a primary dentition:
 Spaced incisors.
 Primate spaces.
 Shallow overbite and overjet.
 Flush terminal plane.
 Vertical inclination of the anterior teeth.
 Ovoid arch form.

61. SPACING
 In a primary dentation stage a child may have generalised
spacing; no spacing; localised spacing or crowed dentation.
Spaced dentition is supposed to be good as spaces in
between the teeth can be utilized for adjustement of
permanent successors which are always larger in size
compared to deciduous teeth.
Generalised spacing occurs in almost 2/3rd of the children
refered to as physiological spaces or developmental spaces
 Localised spaces like primate space are also seen

62. Also called simian space or anthropoid
space
Seen in about 87% cases.
In the maxillary arch it is present
between lateral and canine.
In the mandibular arch seen between
canine and 1st decidious molar.
This space is used up by the developing
larger permanent teeth.
PRIMATE SPACE

63. OVER BITE
 It is the amount of vertical over lap between maxillary and
mandibular central incisors.
 Deep bite may be seen in the initial stages of development.
 It is assentuated by the fact that decidious incisors are more
upright with the lower incisor edges almost contacting the
upper cingulum.

64. • This deep bite reduces later due to:
1. Eruption of decidious molars
2. Attritiion of incisors
3. Forwad growth of mandible
• In about 24% of the children open bite is noted due to
various HABITS.

65. FLUSH TERMINAL PLANE:
Both maxillary & mandibular planes are
at the same level anterio-posteriorly.
Mesial step terminal plane:
Maxillary terminal plane is relatively
more posterior than the mandibular
terminal plane forming a mesial step
Distal step terminal plane:
The maxillary terminal plane is relatively
more anterior than the mandibular
terminal plane.

66. ERUPTIONSEQUENCE OF PRIMARY TEETH

67. MIXED DENTITION PERIOD
This stage starts with the eruption of the permanent 1st
molar by the age of 6 years to the completion of exfoliation of
all decidious teeth at the age of 12-13 years.
In the early part of mixed dentition there may be a
temporary open bite usually due to incomplete eruption of
incisors or a persistent habit.

68. The period during which both primary and permanent
teeth are in the mouth together.
Those permanent teeth that follow into place in the arch
once held by a primary tooth are called SUCCESSIONAL
TEETH.( Incisors, cuspids and bicuspids)
Those teeth that erupt posteriorly to the primary teeth
are termed as ACCESSIONAL TEETH.

69. First transition period:
Emergence of 1st permanent molar
Incisors transition
Establishment of occlusion
Inter transition period
Both sets of teeth present
4 permanent incisors & 1st permanent molars present
Decidious canines and 1st & 2nd molars
Second transition period
Emergence of bicuspids, cuspids,& second
permanent molar.
Establishment of occlusion
PHASES OF MIXED DENTITION

70. Emergence of 1st permanent molar:
Erupts by around 6th year of life
Its location & relationship depends upon the distal surface
relationship between upper and lower second decidious molars.
The distal surface of these decidious 2nd molars guide the
erupting permanent molar into 3 relations:
FIRST TRANSITIONAL PERIOD

71. Ideally the eruption of permanent molars into a class I
realtionship is desired. Since the flush terminal relation is more
common in deciduous dentition ,it is more Common for
permanent molars to erupt into an end-to-end relationship. The
desired Class I relationship established by following ways:
Early mesial shift
If the deciduous dentition is spaced with a flush terminal
relation of the 2nd deciduous molar, then the eruptive force of
the 1st permanent molar causes the closing of any existing
spaces.
That is closure of the PRIMATE SPACES. Mesial to the
deciduous canine in the max. arch and distal to the dec. canine
in the mandiular arch.

72. ARCH LEEWAY SPACE
MAXILLARY 1.8 mm
(0.9 mm in each arch)
MANDIBULAR 3.4 mm
(1.7 mm in each arch)
The combined mesio distal width
of the permanent canines and
premolars is usually less than that
of the decidious canines & molars.
This surplus space is called as
leeway space of nance.
Late mesial shift

73. Rate: Growth between the maxilla and the mandible is not
the same.
The growth of the mandible is twice that of the maxilla
during development of dentition.
Shift which brings the mandible forward causing the END
TO END molar relation of the mixed dentition to change into
a class1 in the permanent dentition.
Differential growth of maxilla and mandible

74. Combination
• A modest change in the molar relationship can be
produced by a combination of:
1)Differential growth of the jaws
2)Forward movement of the lower jaws.

76.  Utilization of interdental spaces seen in primary
dentition.
 Inter-canine width growth -Notable amount of growth
occurs with eruption of permanent incisors and canines.
sex Dental arch width increses
Between 2-18
year
males Maxilla
mandible
6mm
4mm
female Maxilla
mandible
4.5mm
4mm
INCISAL TRANSITION

77. Intercanine arch length increase-
•When permanent incisors erupt, they
assume a somewhat more anteriorly
inclined position than deciduous
incisors.
•This position of the incisors average
2.3mm and results in an increase in
intercanine arch length of approximately
3mm without any change in intercanine
width.
•Inter incisal angle between maxillary
and mandibular incisors in primary
dentition is 150 degrees and 123 degrees
in the permanent dentition

78. INCISAL LIABILITY-The unerupted permanent incisors are
larger than the decidious incisors.
•The difference between the amount of space needed for
accomodation of incisors and the amount of space available is
refered as incisal liability.
arch incisal liability
MAXILLA 7 mm
MANDIBLE 5 mm

79. INTER-TRANSITIONAL PERIOD
This is a latent period with no exchange of teeth taking
place.
Permanent incisors and 1st molar are present.
Decidious canine, 1st & 2nd molars are present
This phase during mixed dentition period is relatively
stable and no change occurs.

80. SECOND TRANSITION PERIOD
Characterised by replacement of decidious canines & molars
by premolars and permanent cuspids respectively.
Eruption of the non succedenous teeth i.e., 2nd molars.
Establishment of proper occlusion

81. As the developing permanent canines erupt, they displace the
roots of the lateral incisors mesially and inturn on to the central
incisors.
This causes the flaring up of the incisor crowns.
Thus causing a midline diastema
UGLY DUCKLING STAGE

82. This situation is being described by broadbent as ugly
duckling stage.
This occurs around the age of 8-9 years
This corrects by itself when the permanent canine erupts
completely.

83. PERMANENT DENTITION STAGE
All permanent teeth are formed around teeth
This stage begins with the exfoliation of last primary Teeth
and eruption of all Permanent teeth except 3rd molar.
The important characterstics of normal occlusion in permanent
dentition were:
Described by andrew’s in 1972 as 6 keys of occlusion.

84. ERUPTIONSEQUENCE OF PERMANENT TEETH

85. MOLAR RELATION: Mesiobuccal cusp of
upper 1st molar occluding in the
mesiobuccal groove of lower 1st molar
CROWN ANGULATION: Gingival part of
the long axis of the crown must be distal to
that of Occlusal part
CROWN INCLINATION: gingival portion
of crown labial to occlusal portion
Labio-lingual crown inclination
Maxillary incisors
Positive inclination
Mandibular incisors
Slightly negative inclination.

86. ABSENCE OF ROTATIONS
ABSENCE OF SPACING
CURVE OF SPEE: Curve of Spee
not exceeding 1.5cm.
The depth of the curve of Spee ranges from a flat
plane to slightly concave surface.

87. MOLAR RELATIONS
 Proposed by Dr. Angle in 1899 depending
on 1st molar relationship for permanent
dentition
 CLASS 1
 CLASS 2 DIV 1
DIV 2
 CLASS 3 TRUE
PSEUDO

88. Curve of spee: anterio posterior
curve passing through the buccal
cusps of premolars and molars on to
the anterior border of ramus to end
on the center of condyle.
Curve of wilson: it is a medio
lateral curve passing through buccal
to palatal and then palatal to baccal
of the other side.
Curve of monson: it is a
combination of both medio lateral
and anterioposterior curve to form a
8 inch sphere with center on
glabella.
COMPENSATORY CURVES

89. CONCLUSION
 Occlusion ,good or bad is the result of an intricate and
complicated synthesis of genetic and environmental
relationship at work through out the early developmental
stages of childhood and young adulthood.
So, understanding the concept can have a far reaching
implications in diagnosis, treatment planning and prognosis of
malocclusion

90. Thank you