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International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 5. Hakodate 1998 
Kinematic Analysis of Lips during Mastication by Two Infrared CCD Cameras 
*Y Hirano, S.Minakuchi, T.Sekita, M.Fujimoto, K.Miyashita and K.Kobayashi 
Department of Geriatric Dentistry, Faculty of Dentistry, Tokyo Medical and Dental University 
1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549 
Tel : +81-3-5803-5561 Fax : +81-3-5803-0208 
JAPAN 
E.mail : y.hirano.gero@dent.tmd.ac.jp 
Commision V, Working Group 4 
KEY WORDS: Lip Movement , 3-D Motion Capture, Denture 
ABSTRACT 
The purpose of this study was to analyze the kinematic difference of lip before and after clinical treatment by the 3-D 
motion capture system. The approach employed in this analysis was as follows. The subjects were 5 volunteers who 
wanted to remake the dentures and three types of foods were selected by the texture. The 3-D motion capture system was 
composed of two infrared CCD cameras (Elite System, Bioengineering Technology & Systems Co., Italy) and was able 
to recognize multiple moving targets and calculate their 3-D coordinates. The features of this system were that no limits 
existed about number of markers that could be recognized in a single frame and that the special processing avoids 
problems related to white areas belonging to the background. The targets were hemispheres and covered with reflecting 
material. These were small enough not to hamper the mastication. The measuring points were mouth corners and chin. 
The data were collected before and after remaking dentures and were compared about velocity, rhythm and quantity of 
movement. It was found that lip movement was more active in the case of old dentures than new dentures. The result of 
this experiment showed that new dentures were fit well and lesser movements were required for the mastication. 
1. INTRODUCTION 
2. METHOD 
In dental region, mastication is one of the most impor- 
tant themes. There were plenty of studies about it. But it 
was few known how to make a bolus. When you eat some- 
thing, first you put it on the tongue, the tongue put it on the 
teeth, and bite it. The cheek and the tongue work to keep 
food on the occlusal table of the teeth. Especially a few 
papers reported the movements of the soft tissue, which 
are lip, tongue and cheek, because it was very difficult to 
measure the soft tissue without harm. To analyze the move- 
ment of soft tissue is very useful for oral rehabilitation. If 
teeth were lost, there will have space. The space must be 
filled, but it must not be neither overfilled nor underfilled. 
The dentures should use space without interfering with 
the action of oral or facial structure. However there had 
been quantum jump of remote sensing in this decade. 
Thus no heavy device were needed on measurement. At 
first we used two CCD-video tracker and coordinate three- 
dimensional data in real time. We reported the movement 
of mouth corner of normal persons". But that system could 
track only a few targets. This time we got a new motion 
capture system, which is able to catch many targets, and 
measured the movement of the lip. 
2.1 The Motion Capture System 
A 3-D optical motion capture system consists of two in- 
frared TV cameras (Elite System, Bioengineering Tech- 
nology & Systems Co., Italy). The motion capture system 
can recognize multiple moving targets and calculate their 
3-D coordinates in rea! time (Fig. 1). To reduce background 
   
   
Infrared CCD Camera 
The purpose of this study was to analyze the kinematic Analytical PC Processor Unit 
difference of lip before and after clinical treatment by the 3- 
D motion capture system. Fig.1 Motion Capture System 
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