Development_of_Occlusion.pptx by Sahil khan...

Development of occlusion
By Md Ashiqur Rahman
1st year pgt
HIDSAR

 The term occlusion is derived from the Latin
word, ‘occlusio’,defined as the relationship
between all the component of the masticatory
system in normal function,dysfunction and
parafunction.
 Angle defined occlusion as the normal relation of
the occlusal inclined planes of the teeth when
the jaws are closed.

The static relationship between the incising
or masticating surfaces of the maxillary or
mandibular teeth or tooth analogues.(gpt)

Ideal occlusion :Preconceived theoretical
concept of occlusal structural and
functional relationship that includes
idealized principles and characteristics that
an occlusion should be
Physiologic occlusion: one that deviates in
one or more way from ideal yet it is well
adapted to that particular environment and
is esthetic and shows no pathological
manifestation.
Young Jl physiologic occlusion J Am Dent 1926

Functional occlusion: An arrangement of
teeth which will provide highest efficiency
during excursive movements of mandible
which is necessary during function.
Balanced occlusion: An occlusion in which
balance and equal contacts are maintained
throughout entire arch during all excursion
of mandible.

Centric occlusion :Maximum intercuspation
of dentition irrespective of condylar
position
Centric Relation: the position of condyle in
glenoid fossa when they are in their most
anterosuperior position against the slope
of ementia with the articular disks properly
interposed.Okeson describes it as most
musculoskeletal stable position of condyle.
Crawford S D Condylar axis position as determined by the occlusion and
measured by cpi instrument sign and symptom of tmd

In 1899, Edward Angle was the first to
describe occlusal relationship.
The first significant concept to developed
to describe optimum functional occlusion
was called “balanced occlusion”.
It was developed for complete denture
primarily.
Okeson JP. Management of Temporomandibular Disorders and
Occlusion. 6th ed. St. Louis: Mosby; 2003.

Unilateral balanced occlusion also known
as group function.
Widely accepted method in restorative
dentistry.
Concept originated by the works of
Schuyler 1953.
All teeth on working side to be in contact
during lateral excursion.no teeth contact
on non working side.

The absence of contact on the non
working side prevent those teeth from
being subjected destructive oblique force
found in non working interference .
It also saves the centric holding cusp from
excessive wear.

In early 1960 mutual protected occlusion
was advocated by Sears and Stallard.
In this posterior teeth comes in contact at
the end of chewing stroke, minimizing
horizontal loading on teeth.
Concurrently posterior tooth acts as
vertical stop when the mandible returns to
maximum intercuspation.
It cant be used in crossbite.

Development_of_Occlusion.pptx by Sahil khan...

In 1970 , dynamic individualized occlusion
emerged.
It centers around the health and function of
the masticatory system and not on any
specific occlusal configuration.
Okeson JP. Management of Temporomandibular Disorders
and Occlusion. 6th ed. St. Louis: Mosby; 2003.

o Predental stages or
mouth of neonate (0-
6months)
 Deciduous dentition
stage(6months -6years)
 Mixed dentition
stages(6years-12years)
-First transitional stage
-inter transitional stage
- Second transitional stage
 permanent dentition
stage

• Pre dentate stage refers
to the period from birth
till the eruption of first
deciduous tooth in the
oral cavity.
• Ideally ranges from birth
to 6 months but a delay
in eruption of first
deciduous teeth by 4-10
months is considered
normal.

 The alveolar process
at the time of birth are
known as gum pads.
 These are pink, firm
and are covered by
fibrous periosteum.

Gingival groove-
Dental groove-
Transverse grooves-
Lateral sulcus-

 The lateral sulcii are
useful in judging the
inter arch relationship
at a very early stage.
 The lateral sulcus of
mandibular arch is
normally more distal
to that of maxillary
arch.

Friel.S Development of Ideal Occlusion of the gum Pad and teeth

 At rest
• Anterior open bite
• Contact occurs between
upper and lower arch in
the first molar region
• Tongue is interposed
between the space.
• The upper gum pad is
larger anteroposteriorly
and transversely than the
mandibular gum pad so
there is overlap at the
front and the sides .

- Development of primary dentition and
occlusion
• the primary teeth begins to erupt at the age of
about 6 months. The eruption of all primary teeth
is completed by 2 half – 3 half years of age when
the second deciduous molars come into occlusion.
• The mandibular central incisor are the first teeth to
erupt in oral cavity.
• The sequence of eruption of deciduous dentition is
A-B-D-C-E.

 Space usually exist
between deciduous
teeth.
 physiological spaces
or developmental
spaces.

Nelson SJ,Ash MJ “wheeler Dental Anatomy,physiology and

 Spacing is invariably
seen mesial to
maxillary canine and
distal to mandibular
canines.
 These physiological
spaces or simian
space or anthropoid
space as they are
commonly seen in
primates

 Deep bite-when the primary incisors erupt the over bite
is deep.This could be due to the vertical inclination of
the primary incisors.over the period of time,this deep
bite reduces due to two reasons-
1.eruption of primary molars
2.Rapid attirition of incisors.
3. Forward movement of mandible due to growth
 At about six years of age ,there may be an edge to
edge relationship.
 Overjet- overjet is initially more in primary dentition.The
overjet decrease with the movement of the whole
dental arch anteriorly. The average overjet in primary
dentition is 1 to 2mm.

Flush
terminal
76%
Mesial
step
14%
Distal
step
10%
Baume LJ. Physiologic tooth migration and its significance for the
development of occlusion. J Dent Res. 1950;29:123–32

 Transition form the primary dentition to the
permanent dentition begins at 6years of age
with the eruption of the permanent first molars
and permanent incisors.Early during this
period of time ,many children experience the
eruption of four permanent first molars and
the exfoliation of the mandibular central
incisors.
 It is the period during which both primary and
permanent teeth are present in the mouth.

This stage of occlusal development
can be divided into the three stages-
1) First trasitional period
2)inter-trasitional period
3)second trasitional period.

This period makes the first exchange of
teeth which begins by 6 years of age and
is usually completed within two years.
important steps -
The eruption of first permanent molars
The replacement of incisors.

The location and relationship of the first
permanent molar depends much upon the
distal surface relationship between the
upper and lower second deciduous molars.
The first permanent molar guided into
position by distal surfaces of the second
deciduous molar

 Flush terminal plane.
 The shift in molar from a flush terminal plane to a
class I relation can occur in 2 ways.
 Early sift 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 class1 molar
relationship. since this occurs early in the mixed
dentition period it is called early shift.

 Mesial step: In this type of relationship the distal
surface of lower second deciduous molar is more
mesial than the upper .
 Then the Ist permanent molar erupts directly into
Angle 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 persists, it can lead to an angle
Class III molar relation . If the forward growth of
mandible is minimal it can establish a class I molar
relation

Distal step terminal plane :This is
characterized by the distal surface of the
lower 2nd deciduous being more distal to
that of the upper. Thus the erupting 1st
permanent molar may be in Angle class II
occlusion.

Proffit RW
“contemporary
Orthodontics”

Flush terminal plane
Mesial step
Distal step
Class1 56%
Class II 44%
Class I > ClassIII
Class II
Nelson SJ,Ash MJ “wheeler Dental Anatomy,physiology and
occlusion”9:279;2010

 Sir Warren mayne (1969)
 The deciduous incisors are replaced by the
permanent incisors.The permanent incisors are
considerably larger than the deciduous ones .
 The difference in amount of space needed for the
accommodation of the incisors and the amount
and the amount of space available is available is
called incisal liability
 The incisal liability is about 7mm for maxillary arch
and 5mm for mandibular arch.

• Utilization of interdental space seen in
primary dentition
• Increase in inter canine width: During the
transition from primary to permanent incisors
an increase in inter canine width has been
observed

Change in incisor inclination : one of the
difference between primary and permanent
incisors is their inclination. The primary
incisors are more upright than the
permanent incisors . Since the permanent
incisors erupt more labially inclined they
tend to increase the dental arch perimeter

Broadbent phenomenon 1937
Self correcting annomaly

 In this period the maxillary and mandibular
arches consist of sets of deciduous and
permanent teeth. Between the permanent
incisor and 1st molar are the deciduous molar
and canine. This period is relatively stable.
 The anteroposterior relation between the 2
jaws is not fixed in occlusion . A fixed
intercusp relationship is absent in absence of
interference the mandibular teeth attains
more mesial position.

 Replacement of the primary canines and
molars.
10-12 years of age.

 The combined mesiodistal
width of the deciduous
canine,I and II primary
molars is greater than the
combined mesiodistal width
of the permanent canine ,I
premolars and II premolars.
This is called leeway
space of nance.
 In the maxillary arch -
0.9mm on one side,totaling
to 1.8mm.
 In the mandibular arch-
1.7mm on one side,totaling
to 3.4mm.

Change in molar relationship from mixed dentition to
permanent dentition-
There are two important contributors to the molars
transition-
1. late mesial shift of the molar- After the shedding of
primary II molar,the first permanent molar shift
mesially.This mesial shift of the lower molar is more
when compared to upper molars because of the
more amount of leeway space.
2. Differential growth of mandible relative to maxilla
is the second contributor.Because of the
cephalocaudal growth,mandible grows more than
maxilla.

All the 28 permanent teeth are seen in
dental arch.
12-14 yrs of age.
The eruption sequence maxillary arch 6-
1-2-4-3-5-7
Mandibular arch 6-1-2-3-4-5-7

The last major change that occurs in the
occlusion of the permanent teeth is the
result of wear-wear of the cusps and
interproximal wear.
The wear of the cusps shortens the height
of the teeth so that in occlusion the
mandible swings further up, and
consequently forward, and the incisors
meet edge to edge.

The interproximal wear appears to reduce
the mesiodistal diameters of the maxillary
and mandibular teeth, so that the length of
the arches decreases.
Individual variation are considerable.

 Andrew 1972
 Key 1 Molar relationship
 The distal surface of the
distobuccal cusp of the upper first
permanent molar made contact
and occluded with the mesial
surface of the mesiobuccal cusp of
the lower second molar.
 The mesiodistal cusp of the upper
first permanent molar fell within the
groove between the mesial and
middle cusps of the lower first
permanent molar. (The canines
and premolars enjoyed a cusp-
embrasure relationship buccally,
and a cusp fossa relationship
lingually.)

 Crown Angulation “Mesiodistal tip”
 The gingival part of the long axis of
the crown must be distal to the
occlusal part of the line
 The long axis of the crown for all
teeth,except molars, is judged to
be the middevelopmental ridge,
which is the most prominent and
centermost vertical portion of the
labial or buccal surface of the
crown.
 The long axis of the molar crown is
identified by the dominant vertical
groove on the buccal surface of
the crown.

 Crown Inclination (labio-
lingual)
 The maxillary incisors
exhibit a positive crown
inclination while the
mandibular incisors
show a very mild
negative crown
inclination.
 The maxillary and
mandibular posteriors
have a negative crown
inclination

 Occlusal plane
 Acc to Andrew it
should be flat not
exceeding 1.5mm

 In simplest way occlusion is the way the
maxillary and mandibular teeth articulate but
in reality dental occlusion is much more
complex relationship because it involves
morphology and angulation of teeth,the
muscles of mastication, the skeletal structure,
the TMJ and the functional jaw movement.
Understanding it would help us to provide
restoration which is harmonious with the oral
health.

 Young Jl physiologic occlusion J Am Dent 1926
 Crawford S D Condylar axis position as determined by the
occlusion and measured by cpi instrument sign and symptom
of tmd
 Nelson SJ,Ash MJ “wheeler Dental Anatomy,physiology and
occlusion”9:279;2010
 Proffit RW “contemporary Orthodontics”
 Baume LJ. Physiologic tooth migration and its significance for
the development of occlusion. J Dent Res. 1950;29:123–32
 Friel.S Development of Ideal Occlusion of the gum Pad and
teeth 1954
 Okeson JP. Management of Temporomandibular Disorders
and Occlusion. 6th ed. St. Louis: Mosby; 2003.
 Dawson TMJ smile and design
 Balaji 5th edition

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