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Dentures and Targets
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Fig. 2 Data processing
2.2 The Motion Capture System
The Elite system can measure the 3-D coordinates of moving
targets in real time with the frequency of 100 Hz. TV cameras
equipping with CCD sensor are able to work in the infrared
band with an infrared ray filter. The camera emitting a
synchronized flush in front of them can detect the reflected
light rays, and send the images to the main processor, which
finds the coordinates of targets with the practice of the
triangulation.
369
2.3 Targets Construction
Twelve targets were prepared for each subject: For the
elimination of the head movement three targets were attached
to the rim of eyeglasses; Six targets were placed on the metal
frame attached to the labial surface of each denture; For the
measurements of the mandibular movements the remains were
set on the metal frame (equivalent for the mentum and the
mandibular angle), which was adjusted to be in parallel with
the mandibular bottom plane and drawn with gum belts in two
directions from each side, while the head gear was used as the
anchor(Fig. 3).
Fig. 3 One of the subjects in full face
2.4 The Photogrammetry
For the measurement of denture mobility we have to transform
because we set the targets in extra oral area. Using stereo
photogrammetry system (PGman) the coordinate system on the
dentures (representative points: first molars and an incisal
point) and the coordinate system of external oral targets on the
metal frames were united by the least square method.
These relations were represented by the transforming matrix,
with which the loca of the extra oral targets were transformed
to the relative movements of the dentures against patients’
head on the analyzing computer (Fig. 4). The distance between
the subjects and cameras was 40 cm( — h ) , and the precision
of calculation was 0.0005 x h ( 7 0. 20 mm ).
3. MATERIALS AND METHODS
3.1 The Subjects
Three complete denture wearers (62~78 years old) were
selected. Complete dentures were made in the Department of
the Geriatric Dentistry, T.M.D.Univ., and the subjects had
been wearing these dentures for at least 3 months.
The subjects were instructed to tap and masticate test foods
(carrots, fish paste, and raisins) on the unilateral side until it
was ready to be swallowed. The same food was masticated on
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
