optical modeling of extra oral defects / orthodontic courses by indian dental academy

8/12/2019 Optical Modeling of Extra Oral Defects / orthodontic courses by Indian dental academy

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OPTICAL MODELING

OF EXTRA ORALDEFECTS.

INDIAN DENTAL ACADEMY

Leader in continuing dental education

www.indiandentalacademy.com



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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

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optical modeling of extra oral defects / orthodontic courses by indian dental academy

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