Precision of the jaw tracking system JAWS-3D.

The purpose of this study was to measure, under laboratory conditions, the noise level of the optoelectronic jaw-tracking system JAWS-3D, which records the movement of the whole mandible from extraorally placed landmarks. Also, an assessment was made of its accuracy in measuring positions, angles, and velocities. The results showed that the accuracy of JAWS-3D decreased when the distance between the recorded point and the extraoral landmarks increased. The path of a point near to the landmarks was estimated with an error of 0.11%, whereas the error increased to 1.33% when the point was far from the landmarks. The maximum error in angle computation was 0.7 degrees. The velocities calculated by JAWS-3D corresponded closely to the actual ones: mean error of 3 mm/s for velocities up to 80 mm/s. Thereafter, the error increased to reach 26 mm/s at a speed of 210 mm/s.