Development of occlusion is agenetically and environmentallyconditioned process which shows agreat deal of individual variation, andconsequently, for the development ofan acceptable occlusion, quite aremarkable co-ordination of differentevents is necessary.
The term occlusion is derived from theLatin word, “occlusio” defined as therelationship between all the componentsof the masticatory system in normalfunction, dysfunction and parafunction.
PRE-DENTAL PERIOD
THE DECIDUOUS PERIOD
THE MIXED DENTITION PERIOD
THE PERMANENT DENTITION PERIOD
Pre – dental period refer to the birth to
the eruption of the first deciduous teeth
in the oral cavity.
At birth alveolar arches are called GUM
PADS.
In maxilla- horseshoe
shaped
In mandible- U
shaped
They are firm and
pink in color.
These gum pad
develop into two
parts:
A. Labial portion
B. Lingual portion
These two portion are separated from
each other by a dental groove which is
at the site of origin of the dental lamina.
It is divided by transverse grooves those
between into ten segments, each
corresponding to a deciduous tooth sac.
Grooves those between canine and first
deciduous molar segments are of
important in assessing the relationship of
gum pads to each other, they are called
LATERAL SULCI.
During this period there is incresed
anterior positioning of the lower jaw with
relation to the upper jaw.
Dental arches are half round in shape.
No curve of spee.
Shallow cuspal interdigitation.
Slight overjet and overbite.
Vertical inclination of incisors.
No crowding.
Spaced dentition is supposed to be
good as spaces in between the teeth
can be utilized for the adjustment of
permanent successors which are always
lager in size compared to the deciduous
dentition.
Also known as
ANTHROPOID SPACES orSIMIAN SPACE.
In maxilla they exist
between lateral incisor
and canine( mesial to
canine).
In mandible they exist
between canine and
first deciduous
molar(distal to canine).
These spaces arepresent in between
the primary teeth and
play a important rolein the normal
development of the
permanent dentition.
In maxillary arch- 4
mm
In mandibular arch- 3
mm.
The relationship of the distal surfaces of
the maxillary and mandibular second
primary molars is one of the key factors
that influences the future occlusion of
the permanent dentition.
Mesio-distal relation between the distal
surfaces of the upper and lower second
primary molar usually can be classified
into the three types:
The distal surface of lower molar is more
mesial to the upper.
Invariably it is
favorable to guide
the permanent
molar in class I
RELATIONSHIP.
Distal surface of lower molar is more
distal to that of
upper.
It guides the
permanent molar
into class II
malocclusion.
Distal surface of the upper and lower
teeth are in straight
planes or in a same
vertical plane.
It is favorable
relationship to guide
the permanent
molars.
OVERBITE –it isdistance which the
incisal edge of the
maxillary incisor
overlap vertically
past the incisal
edges of the
mandibular incisors.The average
overbite in primary
dentition is 2 mm.
OVERJET - it is the
horizontal distance
between the lingual
aspect of the maxillary
incisors and the labial
aspect of the
mandibular incisor,
when the teeth are in
centric occlusion. The
average in primary
dentition is 1-2 mm.
The relationship of the maxillary and
mandibular deciduous canine is one of
the stable in primary dentition. It is
classified as class I when mandibular
canine interdigitates in embrasure
between maxillary lateral incisor and
canine and class II where mandibular
canine interdigitates distal to embrasure.
The period during which both the
primary and permanent teeth are in the
mouth together is known as mixed
dentition. The permanent teeth erupting
in place of previous deciduous teeth are
the successional teeth, where’s those
erupting posterior to the primary teeth
are called the accessional teeth.
A. FIRST TRANSTITIONAL PERIOD
B. INTERTRANSTITIONAL PERIOD
C. SECOND TRANSTITIONAL
PERIOD
EMERGENCE OF FIRST PERMANENTMOLAR- IN both the jaw, the first
permanent molar erupt more or less in a
perpendicular orientation to the occlusal
plane. By the time first permanent molar
erupt any initial spaces between the
deciduous molar and canine will
generally have diminished or
disappeared.
Ideally, the eruption of the permanent
molar into class I relationship is desired.
Since the flush terminal relationship is
more common in deciduous dentition, it
is more common for the permanent
molars to erupt into an end to end
relationship is established by the
following ways:
If the deciduous dentition is spaced with
flush terminal relationship of second
deciduous molar, the eruptive force of
the permanent molar causes a closing
any existing spaces between primary
molars or primate spaces effectively
causing a decrease in arch length.
When no space exist, the erupting first
permanent molars is not able to close
the spaces. In these cases when the
primary molar exfoliates the permanent
molar migrates mesially to use up the
LEEWAY SPACE OF NANCE.
The difference between the mesio-
distal width of the
primary canine,first
and second molars
and their permanent
successors.
This averages 1.8 mm in the maxilla and 3.4
mm in the mandible.
The primary secondmolar relationship
can give clues to the
eventual permanent
molar relationship.
During the first transitional period thedeciduous incisors are replaced by thepermanent incisors. The permanent incisorsare considerably larger than the deciduousteeth they replace. This difference betweenthe amount of space needed for theaccommodation of the incisors and theamount of space available for this is called“INCISAL LIABILITY”.
It is about 7mm in maxillary arch and about5mm in mandibular arch.
The incisal liability is overcome by the following
factors:
Utilization of the interdental spaces in
primary dentition
Averages : 4mm in the maxillary arch
: 3mm in the mandibular arch
INCREASE IN INTERCANINE WIDTH
Intercanine width increases by an
average of 6.0mm in a child between 3
and 13 years of age in maxillary arch
and by an average of 3.7mm in
mandibular arch.
The interincisal angle is
150 degree in the
primary dentition
whereas it is about
123 degree in
permanent dentition
which makes
permanent
intercanine arch
length increase by
approximately 3mm.
150 ◦123 ◦
In this period maxillary and mandibular
arches consists of sets of deciduous and
permanent teeth . Between the
permanent incisors and the first
permanent molars are the deciduous
molars and canine. This phase during the
mixed dentition period is relatively stable
and no changes occur.
The second transitional period is
characterized by the replacement of the
deciduous molars and canines by the
permanent premolars and canines
respectively.
Also known asBROADBENT PHENOMENON
Self –correcting malocclusion.
Seen in the maxillary incisor region between 8-9 yr.
Parents are more apprehensive during this stage and consult the dentist.
This is a particular
situation seen duringthe eruption of
permanent canine.
As the developing
canine erupt , they
displace the root of
lateral incisor
mesially. A resultantdistal divergence of
the crown of the two
central incisor
causing a midline
spacing.
The permanent dentition considered
when all the permanent teeth are seen
in the dental arches, often by the age of
12-14 yr of age.
When occlusion of the dentition has
been established, some minor changes
takes place in sagittal, transverse, and
vertical interrelationship.
Dental arches become shorter due to
proximal wear and crowding develops in
mandibular incisor region by 14 yr of
age.
overbite decreases.
overjet decreases by 0.7 mm between
12 -20 yr of age.
Alveolar process may grow in height
beyond 16 yr of age.
Functional variation influence the
occlusal development.
MOST FREQUENT SEQUENCE OF ERUPTION
IN THE PRIMARY DENTITION
UPPER TEETH A B D C E
LOWER TEETH A B D C E
MOST FREQUENT SEQUENCE OF ERUPTION
IN THE PERMANENT DENTITION
UPPER TEETH 6 1 2 4 5 3 7 8
LOWER TEETH 6 1 2 3 4 5 7 8
• TEXTBOOK OF PEDIATRIC DENTISTRY-
NIKHIL MARWAH.
• TEXTBOOK OF PEDIATRIC DENTISTRY-
SHOBHA TANDON.
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