CAD by processing of computed tomography data and CAM of individually designed prostheses.

In the past an economic fabrication of individual prostheses used in reconstructive cranio-maxillo-facial surgery was not possible due to technical deficiencies. Now, through the consistent use of the most modern computer-based techniques developed in the field of industrial engineering, these costs can be reduced to an economic level. Mathematical freeform surfaces models are first created from helical computed tomography data. These serve as the basis for an efficient and idealized construction of prostheses geometries, and provide control-data for a computerized numerical control-fabrication. In 4 clinical cases this new processing technique has successfully been utilized in the fabrication of individually designed prostheses for the reconstruction of skull defects. The range of opportunities offered is reflected not only in the great variety of possible geometric details, but also in the fact that the prostheses may be manufactured--partly using indirect impression-taking techniques--from 3 different biocompatible materials so far and other applications are likely to turn up.