Use of superimposition areas /certified fixed orthodontic courses by Indian dental academy

Use of superimposition areas
to establish treatment design.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Introduction
• Changes due to normal growth and
changes due to various treatment
mechanics are different for each individual
because of individual morphology and
facial type.


Describing the face
There are three basic facial patterns:
• Mesofacial
• Brachyfacial
• Dolichofacial
From the eleven factor summary analysis, five angels are
used to describe the face:
• Facial axis angle
• Facial angle
• Mandibular plane angle
• Lower facial height
• Mandibular arc

1) Facial axis angle
(90° ± 3 °)


2) Facial angle
(87 ° ± 3 °)


Mandibular plane angle
(26 ° ± 4 °)


Lower
facial
height
(47 ± ° 4 °)


Mandibular arc
(26 ° ± 4 °)


Together these five angles determine
weather the facial pattern is meso, brachy ,or
dolicho facial. Approximately 70 % of
malocclusions that we treat fall in meso facial
range.
It is important to establish what the facial
type is because the reaction of treatment
mechanics and the stability of denture is
dependent upon the analysis of facial pattern.

Five superimposition areas
Following the description of the face and
determination of facial type we use five
superimposition areas, superimposing the
TIME ONE tracing against the VTO or any
progress tracings, to evaluate the change
that we expect will occur or has occurred
due to growth or due to treatment
mechanics.

The five superimposition areas are used to
evaluate the face in following order:
•
•
•
•
•

Chin
Maxila
The teeth in mandible
The teeth in maxilla
The facial profile


Superimposition Area 1(Evaluation
Area1)
In normal growth the chin grows down the facial axis and
the six year molars also grow down the facial axis.The
facial axis rotates open or closed from the effects of
mechanics, and other considerations as follows:
• Facial axis opens one degree for 5 mm of convexity
reduction.
• Facial axis opens one degree for 3mm of molar
correction.
• Facial axis opens one degree for 4mm of overbite
correction.
• Facial axis may close with extraction.

Area 2)
The second superimposition area ( Basion –
Nasion at Nasion ) establishes evaluation
area 2 to show any change in the
maxilla( point A ). The basion-nasion-point
A angle does not change in normal
growth.


The following are considered the maximum
range of point A change with various
mechanics :
Mechanics
• HG
• Class II elastics
• Activator
• Torque
• Class III elastics
• Facial masks

Maximum range
• -8mm
• -3mm
• -2mm
• -1-2 mm
• +2-3 mm
• +2-4mm


Superimposition Area 3 (Evaluation
Area 3 and 4)
The Third superimposition area (corpus axis
at PM) establishes evaluation are3&4
which together evaluate any changes that
take place in mandibular denture.
In evaluation area 3, we evaluate whether
we are going to intrude, extrude….
In evaluation area 4, we evaluate the lower
molars to determine what type of
anchorage we need……

Area 5& 6)
• The 4th Superimposition Area
the fourth superimposition area
[palate at ANS] establishes evaluation
area 5 and evaluation area 6,which
together evaluate changes that takes
place in maxillary denture. In normal
growth, upper molars and incisors grow on
their polar axis.

Superimposition area 5(Evaluation
Area 7)
•

The fifth superimposition area (esthetic
plane at crossing of occlusal plane)
establishes evaluation area 7 with which
we evaluate soft tissue profile. In normal
growth ,face becomes less protrusive with
reference to esthetic plane.We use
superimposition area 5 evaluation area 7
to evaluate effect of our mechanics on
soft tissue of the face.

Superimposition and evaluation
demonstration.
Using tracing of M.G.from part 3 VTO, five
superimposition areas and seven evaluation areas to
evaluate that VTO.
IST SUPERIMPOSITION AREA(BA-NA AT CC POINT)
FIRST CHECK POINT
Place your VTO over the original tracing of M.G on
Basion Nasion at CC point. You will see that facial
axis has opened 1or 2 degrees. Therefore the
mechanics will open the facial axis 1 to 2 degrees

demonstration


demonstration
• 2ND SUPERIMPOSITION AREA(BA-NA AT NA
POINT) SECOND CHECK POINT
• Place your VTO over original tracing of M.G on
Basion Nasion at Nasion. Basion-Nasion-Point A
angle does not change in normal growth. As you
look at the tracing you would see that point A
has been reduced by 2mm


demonstration
• 3RD SUPERIMPOSITION AREA(CORPUS
AXIS AT PM POINT) THIRD CHECK POINT
Corpus Axis at PM. It shows that we would like
to tip the lower incisor forward approximately
2mm and bring the lower molar forward
approximately 4mm


demonstration
• 4TH SUPERIMPOSITION AREA(PALATE AT ANS)
FOURTH CHECK POINT.
• Place your VTO over original tracing of M.G on palate at
ANS. Since we are bringing the lower incisors and lower
molar forward , even though this case is class II
malocclusion all we must do is to hold the upper molar to
accomplish the class II correction. The upper incisor
evaluation shows that we are going to retract and torque
the upper incisors .it also shows the potential use of
clssII elastics and torque on upper incisors is going to
reduce Point A

demonstration
• 5TH SUPERIMPOSITION AREA(ESTHETIC
PLANE AT THE CROSSING OF OCCLUSAL
PLANE )
ESTHETIC PLANE where the occlusal plane
crosses it ,we see that reduction of upper
denture results in a great reduction in the soft
tissue profile


Conclusion
• Super imposition can help us to achieve
following objectives
• 1) Basic description of cranial structures.
• 2) Analysis of normal growth change.
• 3) Treatment design
• 4) An evaluation of growth and treatment
results.

Thank you
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Use of superimposition areas /certified fixed orthodontic courses by Indian dental academy

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