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OPTICAL MODELING
OF EXTRA ORALDEFECTS.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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Introduction.
The combination of medical imaging and
rapid prototyping is a fast expanding field with
a large application potential in medicine and
related fields.
Typical applications include the making of 3-
dimentional copies of anatomical structures,
the production of individually designedprosthesis models and the replication of
anatomical objects for educational purposes.
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This presentation highlights about recent
imaging technology and its application in the
field of maxillofacial prosthesis.
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Steps in the fabrication of
Maxillo facial prosthesis.
1) Impression making.
2) Preparing a physical model
3) Fabricating a prosthesis pattern. 4) Final prosthesis.
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conventional impression materials such as
Silicones
-Irreversible hydrocolloidhave been used in the fabrication of Maxillo
facial prosthesis.
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Conventional Impression
Procedure.
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Disadvantages of using the
impression materials
-Discomfort to the patient.
-Testing the ability of the clinician. -Structural variability of the material leads
to inaccuracies of the fitting of the prosthesis.
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The next generation CT & MRI over come the
difficulties encountered while using the
impression materials.
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CT & MRI scan the defective area & a CAD
model of the defective area is reproduced,
from which a CAD model of the prosthesis
pattern is designed & we get the prosthesis
pattern by a procedure known as rapid
prototyping.
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CT SCAN
Computed Tomography is based on the x-rayprincipal:
x-rays pass through the body they areabsorbed or attenuated (weakened) at
differing levels creating a matrix or profile ofx-ray beams of different strength.
This x-ray profile is registered on film, thuscreating an image.
In the case of CT, the film is replaced by adetector which measures the x-ray profile.
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But the only disadvantage is, the patient is
exposed to radiation
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This disadvantage is overcome by optical 3-
dimentional scanner, which uses optical light
as the source.
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It is a mobile, multiview 3-D measuringsystem based on self-calibrating fringe
projection technology
It facilitates the fully automatic recording ofthe body part from various direction in one
measuring process
The maximum field diameter of the system is650 mm. Therefore, the complete human
face can be recorded in a single operation.
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The face is illuminated by two grating
sequences (grey code combined with four,
90-degree phase-shifted sinusoidal
intensities).
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The observing cameras capture these fringe
pictures simultaneously, resulting in at least 4
phase values for each pixel of the camera. Using these phase values, the 3-D
coordinates are calculated.
In the kolibri-mobile system, the object isilluminated from different directions by means
of a network of fixed mirror.(M1, M2, M3, M4,
M5)
The switching of the projection direction isdone by the rotating central mirror M1.
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Optimum measurements of an extraoral
defect involves 4 cameras and 5 projection
directions.
Using this technique, the whole body view is
obtained automatically without any additional
software manipulations.
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The duration time of recording up to the 3-D
point cloud is approximately 20 seconds.
The measuring accuracy as by the
manufacturer to be less than 100um.
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The body part is exposed to structural light
and is recorded optically.
The data is transferred and saved as an arg-
file. These data is changed into ASC2 format
on the computer.
Process the data with software (SURFACER,version 10.5).
And a CAD model is generated.
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RAPID PROTOTYPING
The generated CAD model is converted into
a physical model by means of a rapid
prototyping procedure using a 3-D model
printer.
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3-D model printer used
for rapid prototyping to
obtain the physical
model
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Uses of physical model
The pattern of the prosthesis is designed
digitally and the accurate physical model is
obtained
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Thank you
For more details please visit
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