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1. OPTICAL MODELING
OF EXTRA ORAL
DEFECTS.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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2. 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 3dimentional copies of anatomical structures,
the production of individually designed
prosthesis models and the replication of
anatomical objects for educational purposes.
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3. This
presentation highlights about recent
imaging technology and its application in the
field of maxillofacial prosthesis.
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4. 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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5. conventional impression materials such as
Silicones
-Irreversible hydrocolloid
have been used in the fabrication of Maxillo
facial prosthesis.
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8. 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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9. The
next generation CT & MRI over come the
difficulties encountered while using the
impression materials.
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10. 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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11. CT SCAN
Computed
Tomography is based on the x-ray
principal:
x-rays pass through the body they are
absorbed or attenuated (weakened) at
differing levels creating a matrix or profile of
x-ray beams of different strength.
This x-ray profile is registered on film, thus
creating an image.
In the case of CT, the film is replaced by a
detector which measures the x-ray profile.
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13. But
the only disadvantage is, the patient is
exposed to radiation
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14. This
disadvantage is overcome by optical 3dimentional scanner, which uses optical light
as the source.
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15. The
optical 3-dimentional scanner is a newer
device used to scan the facial defects and
reproduce a CAD model which is used in the
fabrication of Maxillo facial prosthesis.
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17. It
is a mobile, multiview 3-D measuring
system based on self-calibrating fringe
projection technology
It facilitates the fully automatic recording of
the body part from various direction in one
measuring process
The maximum field diameter of the system is
650 mm. Therefore, the complete human
face can be recorded in a single operation.
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18. The
face is illuminated by two grating
sequences (grey code combined with four,
90-degree phase-shifted sinusoidal
intensities).
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19. 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 is
illuminated from different directions by means
of a network of fixed mirror.(M1, M2, M3, M4,
M5)
The switching of the projection direction is
done by the rotating central mirror M1.
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22. 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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23. 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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24. The
body part is exposed to structural light
and is recorded optically.
The data is transferred and saved as an argfile. 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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28. 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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29.
3-D model printer used
for rapid prototyping to
obtain the physical
model
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30. Uses of physical model
The
pattern of the prosthesis is designed
digitally and the accurate physical model is
obtained
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31. Thank you
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