The accuracy with which the human condyle can be expressed in the coordinate system of JAWS3D using a unilateral fiducial marker

Previous studies have indicated that the selection of condylar referencing points can significantly influence condylar point trajectories, and the use of radiographically determined condylar points is essential for accurate r epresentation of condylar movement. The aim of this investigation was to de termine the accuracy with which the three-dimensional locations of condylar points could be determined in the coordinate system of the JAWS3D tracking device when an ipsilateral fiducial marker is used. A perspex mandible con taining condylar radiographic markers was constructed. A JAWS3D target fram e and a fiducial marker, supporting radiographic markers, were secured to t he perspex mandible. The image data from computer tomography scans of the c ondyles and fiducial marker, together with photographs of the fiducial mark er and the JAWS3D target frame were used to calculate condylar point coordi nates in the JAWS3D coordinate system. These data were then compared with t he data obtained by direct measurement of the condylar radiographic markers in the JAWS3D coordinates. The results suggest that a unilateral fiducial marker is sufficient to allow the registration of ipsilateral condylar poin t coordinates to an accuracy of similar to 1.0 mm.