Abstract
This study tested the accuracy of a series of modifications made to an available jaw tracking system (TM Jawgraph) . Namely, pyramidal-shaped sets of markers were designed to allow 3-D measurements by a geometrical method; each of these sets carried four infrared-light-reflecting passive markers whose diameter is 3 mm. The total weight of each set including the connection rods is merely 2g. These sets of markers were expected to provide not only 6-degree-of-freedom recordings of the mandible, but also of coordinated head movements and of objects confined within a small predetermined area. A computer software was also made to analyze the markers' 3-D movement. The CCD cameras in this system require a 200×200×200mm field.
Verification of the accuracy of this system for measuring jaw movements was made with translation tests using pulse stages. The error of measurement among trials was calculated for several positions. The average error in the horizontal axis, between the frontal and the posterior planes was 0.3mm, and 0.2mm for the vertical and horizontal axes between the right and left sides of the measuring field. From this results we concluded that this system allows a precise estimation of 3-D jaw movement with the lightest device attached to the teeth that is available today.
