Movements of soft tissues surrounding the oral cavity, especially lips and
cheeks, have a strong influence on mastication and phonetics. They also inf
luence the relationship between a denture and its oral environment. The pur
pose of this study was to develop a three-dimensional measuring system for
soft tissue movement. This system consisted of two video trackers placed st
ereographically and a computer. In addition, one video tracker was connecte
d for measuring mandibular movements. The accuracy of this system was evalu
ated using computerized XYZ pulse stage. The resolution of this system was
0.10 x 0.10 x 0.10 mm, when the measurement was carried out in the area of
the 24.0 (X) x 20.0 (Y) x 20.0 (Z) mm with a working distance of 500 mm and
a frequency of 120 Hz. In the present study, the lip movements of a dentul
ous subject with mandibular movements during chewing peanuts were analysed
using this system. The new system demonstrated its value for analysing soft
tissue movement.